My parents moved internationally twice, and so have I and both of my sisters.

From our collective experiences, I'd recommend the second option. Find a place to rent for a year, then house hunt without the pressure, and after having a much better idea of good locations, commute-times, schools and the option of a whole year to spot potential good bargains (if that's your wont). One year is short enough that you can put up with the flaws you're likely to find with the rental place... and possibly even get a better idea of what you "really" want in your house anyway.

As to moving everyone vs following on - that's very dependent on the individuals involved. It's very hard for some people to live apart. It's very disruptive for kids to leave school partway through... you'll have to decide what's best for your family there.