an you perplex up your range to make a Barrier? If so, what happens at the end of your turn when Perplex ceases to function?

Yes, that's fine, and nothing happens when the Perplex fades---you don't need to maintain your range any more than you need to maintain your line of fire. You must meet these requirements when you create the Barrier, but only then.

I thought LOF wasn't required for barrier - hence the coolness of soaring figs w/ Barrier - did this change?

Actually, yes it did change. Though it changed a while ago.

You now need line of fire for the first square of a barrier to be placed in and all squares must be in the figures range at the time of creating the barrier.

LoF's been required for Barrier for a while now, like shock man x said. As for how that affects soaring figures---not a great deal. Line of fire from a soaring figure to the ground is not blocked by grounded or elevated figures, so you still have a good deal of leeway when creating a Barrier from soaring.

Ahh, thanks for clearing that up.