Some more ideas
1. Let guests do the Fiquiz quiz (they is no harm and some people might be too lazy or do not want to register Plus if someones quickly visits the website and doesn't want to keep on registering so many different sites ). i dont think guest can do harm by doing the quizes[/quote] This can be considered. Obviosly things have to be considered.
2. trial guests posting new threads (its up to you and if it gets out of hand you can stop it). its similar to posting on threads but could be more harmful
an option. Been done in the past, bad choice.
[quote]about the editing you can make it so that a guest can anly edit their own post