Oh god please yes. I'm planning on talking about the limits of our observations in our own solar system and what is possible versus excluded both now and in the past, as well as origin of life research and the history of the scale and complexity of Earth's biosphere. Will PM you.

I don't know how exactly quantitative I can get beyond 'small stars are bad' - I don't think there's a lot of collation of the necessary data. I can try.

• Stars bigger than ~1.2 solar masses (in the middle of spectral type F) would cook Earth-analogs before we had large amounts of multicellular life, though that might not be true for all theoretical lifebearing worlds.

• http://www.solstation.com/stars.htm is a fun source for known stars in the solar neighborhood as revealed by the Hipparcos satellite dataset. It might not be as rigorous as the datasets themselves but it's certainly easier to navigate. There are at LEAST 1400 stars within 50 light years of the Sun, only ~64 of which are solar type (spectral type G) and about ~46 of which are larger (F,A,B). There's a full 152 (or more! - out at 50 LYs some might be missed) K type stars that are smaller and longer lived than the sun in the same volume that are not smaller to the point of being M dwarf stars. Some of those stars might last up to 30 or 40 billion years, with any one planet possibly being habitable for a reasonable fraction of that time compared to Earth's up to 6 billion years. This does make me wonder if a large fraction of them are unlikely to spawn biopspheres for some unknown or underappreciated reason, or if we just got slightly 'lucky' in that we are in the upper quarter or so of stars that probably spawn complex biospheres in terms of mass, which actually isn't all that weird all things considered.

• One might expect longer-lived K-type stars to have longer-lived biospheres and have a higher chance of spawning intelligent systems, making that 'upper quarter' thing a bit more odd. I have no answer to this. I can randomly speculate though: Maybe planets 'run down' in some way over time in these systems over timescales slightly longer than the Earth has in our solar system before the sun cooks it. Maybe the brightening sun is closely balanced by Earth's cooling geosphere putting out less and less CO2 and other such gases over time and these processes wouldn't balance for as long in a system with a slower-evolving star, such that solar-mass stars are more closely tuned to long-lived biospheres than we expect. Maybe star mass has unappreciated statistical ties to planet types. Or maybe we have just hit on one of the random weird things about our biosphere that given there are so many variables that go into each biosphere you will find a few of that aren't necessarily important but are nonetheless there. With a hundred uncorrelated variables, you'd expect us to be in the 95th percentile of several of them...

• Maybe stars of masses that we see as only sometimes being flare stars is a case of individual stars occasionally flaring regularly and occasionally not over human timescales rather than different stars behaving differently over geological timescales - we've only been watching for a short time.

• Stars smaller than ~0.5 solar masses (M type, red dwarfs) need a planet to be so close in to get an Earthly amount of radiation (< 0.3 AUs) that they probably tidally lock. There's endless arguments as to if that's a no-no or not for complex biospheres and what it means for atmospheres and hydrospheres. They're also often flare stars.

• Red dwarf stars have a longer cooldown period from formation, which was done in our system pretty much during the planetary accretion stage, and might complicate habitability arguments.

...Conclusion: there's too many maybes here.

PS: I can't freaking wait for the GAIA mission dataset to come back, it'll be the greatest star map ever created by orders of magnitude...

ANOTHER EDIT: A lot of interesting discussion in the commentary of http://www.centauri-dreams.org/?p=9032 - looks like the limit of tidal locking for something with terrestrial illumination is closer to 0.7 solar masses.

YET ANOTHER EDIT: Another visualization of nearby star systems: http://www.atlasoftheuniverse.com/50lys.html

That depends on something called the "initial mass function" for a star forming region - the frequency distribution of masses produced. See http://model.galev.org/help/help_imfs.png for two estimated mass functions for our galaxy.

Until recently the consensus was that since the initial mass function was pretty similar throughout our own galaxy under very different environments, it should be similar in other places too. More recently there's been some controversial claims that 'Early type' (elliptical) galaxies may have a systematically different mass functionn than spirals that also varies by galaxy mass, see http://astrobites.org/2012/02/16/the-imf-is-not-universal/ . Other research seems to contradict this, see http://astrobites.org/2014/12/08/counting-stellar-corpses-rethinking-the-variable-initial-mass-function/ . These papers become technical to a point at which I get lost pretty easily in reading them. If I am reading the paper referred to in the first link correctly though, their findings if true are consistent with one of two scenarios: either the mass functionin massive elliptical galaxies is biased towards the formation of large amounts of small stars, or it is biased towards the production of large amounts of large stars which are now dead and contributing excess compact mass in the form of dead star remnants. Both would be consistent with the data (which comes in the form of ratios of luminosity to galactic mass) but a mass function like that of most spirals would not be.

If the mass function stuff turns out true, I'm pretty sure it would distort the shape of the curve of star formation referenced in this post one way or another, but not change its ultimate form.

They're great candidates for life, especially given mounting ideas on the origin of life possibly being tied up with geochemistry and geology.

They're lousy candidates for big biospheres that utterly transform the geochemistry such that you could see it far away like ours has, or for complex life, since the total energy flux available in potentially clement environments is miniscule compared to here. But Earth's biosphere had to start with something a lot like the energy sources you have in the icy moons, not photosynthesis.

Preview:

Given the current state of origin-of-life research that is starting to support tying early biochemistry to geochemistry rather than 'primordial soup' type situations and the apparent speed of life's origin on Earth, it's easy to imagine life arising multiple times in multiple places in our solar system. Can't say that it did or didn't though, we'd need way more data.

Given the differences between Earth and other places in our solar system, there's definitely not going to be any other big biospheres with huge amounts of biomass and complexity that utterly remake the geochemistry of a body; instead any other biospheres would necessarily be both tiny and very hard to see due to hanging onto small matter and energy fluxes in protected regions of their homes.

Given the sheer difficulty of exploring other bodies for these small things in protected niches, it's entirely possible that we could've missed several of these small biospheres (past or present) so far. As such I would not be terribly surprised at future evidence of these things. Mars is great because you've got an exposed surface that may have been very different in the past that you can look for traces on plus inklings that there could still be productive niches in places its not inconceivable you could look at, it's 'close' (all things considered), and the interesting spots aren't all under kilometers of ice. It's also still an entire planet that has barely been looked at up close at all so far and where it costs an instrument's weight in gold to send it there.

In the case of Mars, we have an improbable advantage, because there is already a huge industry and body of knowledge devoted to the discovery of organic-rich rock deposits in regions that are likely to preserve complex carbon forms. If there ever was an ecosystem on the surface of Mars, Exxon will help us find it.

(Although actually, Mars lacks active tectonic plates, so it's not quite the same problem. But many industry tricks and technologies will transfer seamlessly.)