Do you need to build a legal entity to go out and talk to people etc? A lot of people over here at least get warned against incorporating until they absolutely need to.

That I can't answer, since I'm not familiar with the legal kerfuffle surrounding incorporation in the US. In the UK, incorporating takes about an hour and costs £50, but I hear that it's a lot harder and more onerous in the US.

I don't know about incorporation, but an llc takes about as much in the US. it's not really an easy question generally. I'll probably end up waiting until closer to a 'production' release