Is there a plan for how long it will be e-book only before releasing the real book?
Not yet; the timeframe will depend partly on how quickly readers are finding lingering typos, how many they're finding, etc. It will also depend on how long it takes us to find a hardcopy publisher that we are confident will produce a physical thing that people will enjoy using and looking at.
LessWrong is getting ready to release an actual book that covers most of the material found in the Sequences.
There have been a few posts about it in the past, here are two: the title debate, content optimization.
We've been asked if we'd like to produce the audiobook version and the answer is yes. This is a large undertaking. The finished product will probably be over 35 hours of audio.
To help mitigate our risk we've decided to Kickstarter the audiobook. This basically allows us to pre-sell it so we're not stuck with a large production cost and no revenue.
The kickstarter campaign is here: https://www.kickstarter.com/projects/1267969302/lesswrong-the-sequences-audiobook
If you haven't heard of us before we've already produced some sequences into audiobooks. You can see them and listen to samples which are indicative of the audio quality here.