Spicer (& everybody),
it's just to check everything is working smoothly with the Steam integration, starting with the install process and till the features you listed, also including online play (checking your online account is same either you use Steam account or your MG.com's Key).
As a reminder : I'll publish a link to get your Steam key (hopefully within 2 weeks), and it's at that time that you'll have to grab it. There's no need to post right now, although it's cheering me up to see many people interested like this, so it's still welcome !
Elias,
TE Steam won't support Steam Workshop, so Mod install will still be same than before ; the Mods folder will be either in the Steam's TE folder, or in Windows' User folder (depending if Steam provides write privilege in Steam's TE folder).