1. In XP it's c:\Documents and Settings\username\SendTo, I think. Or c:\windows\SendTo or something. You can add your own links in there to add them to the sendto menu too. Like I used to add Notepad into mine, when I had Wind95. Or add a folder or something. Delete the links from there and it should be gone from the sendto menu.

2. Use Firebird again. Honestly though, I don't know, other than uninstalling the programs. You probably don't want to uninstall your Java VM though. So maybe just ignore the menu items.

3. It's a .reg file? .reg files hold info that can be inserted into your registry. The .reg files themselves aren't accessed by Windows or anything, you just open the file once and Windows will suck the registry info out of them and insert them into the registry itself, and then the file is useless. If you don't need the info that's in the .reg files, i.e. you already inserted that info into your registry and/or you know you don't want to and never will, you can delete them, I'm pretty sure. Then again, I don't know what jv16 Power Tools is, or why you have registry files sitting around that an uninstaller wouldn't delete itself for example.