it won't help you locate the conflicting app. people will often do this just to see if their phone functions properly while in safe mode. if it works fine in safe mode, but not in it's normal state, then there's a good chance there are some conflicting apps. at that point though, you likely need to do a factory reset, and reload a couple of apps at a time. when the phone starts acting wonky, then you've found the app that caused it. i typically never install more than one or 2 apps per day. i then will use the phone for a couple of days before downloading any more. this way, i know which app caused any issues that may arise.
as far as modes go, the only ones i'm aware of are normal (just turn it on), safe mode, and airplane mode (which kills the radios, but you can activate wifi while in airplane mode).