Will you buy an RPG just by the fact that it is an RPG?
No, depends on reviews, type / style of gameplay etc.
How do you decide to buy an RPG?reviews,word of mouth, forums?
I usually go on reviews, demos etc and popularity e.g bought Skyrim just on popularity alone and enjoyed it.
Do you cheat/ use hacks/editors?
No except in very rare cases.
Do you use walk throughs?
Only if I'm stuck on a particular quest but I usually like to figure things out for myself.
Do you download the latest patch before you start a game?
Yes however most games I buy are via steam so this is automatic.
Do you prefer single character or party?
I like both as long as it's a good story based game. I like solo sandbox style games like Skyrim. Especially on the PC as you can download player made content / mods.
Do you prefer single player or multipalyer?
Single player and local co-op with friend. Don't play MMORPG's due to lack of time required to get the most out of them.