I have a bunch of themes downloaded to my multisite. Some are from WPMU and some are not. I have been having some security issues recently and my host tells me it is is because I have too many old themes. I probably do and I know that the one that I am currently using should probably go. But my question is in choosing a new one and in offering themes for my other sites how do I tell which are the good ones and which should be deleted? Is there a place where it shows when they were last updated. I am aware of the change logs, but how should they properly be used. I know some of the themes that came from WPMU but is there even a way to tell where some of these themes came from? I want to choose a better supported theme this time and keep a smaller array of themes for my users that I know will be looked after. I got a pack of, I think it was 100 themes or something like that, I think it may have been called the farm pack, when I first started here. Is that still being updated? I know some of them were broken when the new version of wordpress came out so I already deleted the broken ones.
Please point me in the right direction. Same with plugins. How do I tell if they are not being supported and becoming a security risk.