Will you buy an RPG just by the fact that it is an RPG?

No. First i have to know if it is good or not and what you get.

How do you decide to buy an RPG?reviews,word of mouth, forums?
Forums and also comparing with previous title if it is part of a serie.

Do you cheat/ use hacks/editors?
no

Do you use walk throughs?
With some rpg's yes, because i got stuck or i have the idea i missed something

Do you download the latest patch before you start a game?
Offcourse. Who doesn't? You want to play the game without any big problems.
i also download community made patches, because the game wasn't patched by the developer, like vtm:B for example or gothic III.

Do you prefer single character or party?
I have no preferences towards one or other. I like singleplayer such as TES as partybased like NWN.

Do you prefer single player or multipalyer?
Singleplayer all the way. I have tried a MMO once, Rappelz, but got tired of it.