Sometimes when i play in either single player or multiplayer, the ghost moves like yber crazy fast, which is nice and i'd like it to be like that always. Sometimes it's kind of slow though.

How can i change that? Surely it can't be just my eyes fault

And another question which might be related to this, in multiplayer games it says fps is about ~30, how can i make it go upto 100?

You can switch the game between 30 & 60 FPS in options.

The ghosts slow down when your pc has to do a lot of calculating, so if you've grabbed someone or fighting upclose they can slow right down.

More processing power or turning off un-needed graphical effects can speed it up.

Alright. Where can i switch it to 60 fps though? I can't see it. I have 3.593.

You need to download 3.6x - I think the option first appeared in 3.64

http://www.toribash.com/downloads.php