When I heavily modded Oblivion, a couple times I had to uninstall and then re-install the game.

With steam, if I seriously mess up can I uninstall it and reinstall? Does this work with steam or if I uninstall that's it?

Hope this is in the right forum. I posted here because it wasn't a software issue at this point. Thanks!

Yeah, you can. If you got a game on Steam and lose your CD you can always download it again and reinstall.
Very practical if you move or are traveling alot.

Steam downloads real slow though, so it isn't recommended if you still got the disk.

What you can do is delete your mesh/texture files and mods then re verify game integrity and it will redownload only the needed files.

It's also quite simple to back up your original game files to external drive in case you don't want to have to download them again in the future.

Within the Client you can select "Steam" ->"Backup & Restore Games" (or right click on any game).

As much as a dislike steam, that sounds like a handy feature.