All editing methods are used for different purposes. Some people may prefer using a more advance editing method, so they edit their posts with font/size/bold/color/etc code. But there are other people who just notice a little mistake in their post (like accidentally writing thier instead of there), so they use the quick editing method. I do not know what the third method is though.
Finally finding about some of the bots that are flooding the users online - bytespider apparently is a huge offender here - ignores robots.txt and comes in from a ton of different IPs
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.