I think the first thing is to find out what is using your internal storage. The lack of space (and 68kB is critical) may be the cause of some of your other problems.
One thing to know is that not all of an app is moved to SD when you move it (how much depends on the Android version - 2.2 moves less than 2.3), and either way app data will remain on internal. App data includes messages, contacts, facebook stuff. Social networking apps sometimes consume a lot of space.
You may be able to get some space quickly by clearing app caches. If you don't have a cache cleaning app, just use the manage applications menu, all applications, and go through things like browsers, forum apps, social apps, market/play store and select clear cache on each of these.
To see what's using space, in the same "all applications" view change the settings to sort by size (I think 2.2 allowed you to sort by data size, 2.3 only by total size). That should show you what the big space users are.
P.S. For your email can you not delete these from the server using a PC and then re-sync? Or does your email system not work that way?