I just bought this because I am a fan of fallout 1 + 2 and someone told me it was similar, but generally do not like having to control a whole party. Do teamates act on their own like fallout, and if not, is it viable to play without party memebers?

Party members are treated just like your character. You can enable AI to let them act on their own or and give only commands if you want them to do something else if you wish.
You can solo the game if you want, it won't make the game more difficult (if you create a character with good constitution) but it won't hurt if you keep other party members around in the beginning, just try it out.

You certainly CAN. For the IWD and BG games I often do create solo characters.

For PS:T, though, you'll really be missing out on a lot of stuff by going it alone. The characters are well-written and interesting and many of them are plot-related in some way. You'll miss quite a bit of excellent dialog as well. Since the focus of PST is on the story and characters much more than the combat, I really don't recommend playing solo your first time.

You can, but you'll miss out on a LOT of content. Unlike the Fallout games where companions mostly just tag along as hired guns, in PS:T the companions each have lots of backstory and dialog and can feature quite prominently in the story.

Guess i'll just see where it goes. Dosn't seem to be so combat focused so the party members won't bother me as much. I just don't enjoy managing a whole party in combat, like dragon age.