Steam episode statuses and future eps
 

I got the Steam key for preordering from here, and want to play it. But I got to thinking. If I finish Eps 1 on Steam, how would my decisions carry to future eps if I play from TT download? Would I need to replay eps 1?

They are different builds, so you would have to start over again on the Telltale download version.

Telltale knows this (as they stated this before with other games), so I wouldn't be surprised if the key works for all 5 episodes on Steam. I can't confirm this though, since I don't work for Telltale (and haven't received my key yet so I can't check the e-mail to see if there's anything about it in there).