Let's imagine I've asked a question, and posted it as a 'personal'. Is there a way to revert it to a community one, where I don't receive rep points?
Any help would appreciated.
You can't make questions community wiki (CW) without flagging a mod (not anymore). This is because, in practice, forcing all answers to be CW as well at the whim of the asker is very rarely useful and often counterproductive. So flag the post and explain why you want the question to be CW.
Generally speaking, "I don't want the rep for this" isn't a terribly great reason to make any post CW. For answers, it's occasionally reasonable to make a CW answer based on someone's comment or chat message, but otherwise, the purpose for CW is mostly to encourage freer editing and collaboration on a single question/answer pair. If you don't know for a fact that that's what you need, you probably don't need CW.
If you want to change a post into a community wiki, edit the post and check the box under the bottom right corner of the edit area.