Plugins that break WordPress?

The only way to know for sure is to test the plug-in with your theme.

That said, I tend to look for plug-ins that:

– have been updated recently
– state that they support the latest version of WP
– have good star-rating
– get a fast response time to forum requests by the developer
– have a record of quick updates for compatibility with new versions of WP (you can often tell this by their forum topics or looking in the changelog)
– are by a reputable developer
– are popular (popular plug-ins tend to be fixed quicker if a problem crops up since there’s a large user base)

Yes, and be prepared. When a plugin brakes your site you often don’t have site access through admin. Be sure you know how log in to your hosting account and access your wp installation and the plugins folder. You often need to delete the plugin which caused the crash. however once done, your site will be back to normal, no permenanat damage.(at least not that I’ve ever experienced).

And beware of plugins which haven’t been updated in a year or more. Even if they work, they could have developed a security hole and you would never know untill you get hacked.