All Over The Place - Totally Confused !!

[FirefoxWiz]

Firstly for your bookmark problem, I would begin by creating folders in there. Just rightclick anywhere in the bookmark menu and click New Folder. Then start dragging your bookmarks in.

For the extensions, you can find them here --> https://addons.mozilla.org/firefox/extensions/
I would just get the ones I'd see I needed. Here is a list of mine, incase you'd like to see:

Generated: Fri Mar 23 2007 09:24:33 GMT-0400 (Eastern Daylight Time)
User Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.3) Gecko/20070309 Firefox/2.0.0.3
Build ID: 2007030919

Enabled Extensions: [21]
- Add Bookmark Here 0.5.5
- BBCodeXtra 0.2.5.6
- ColorZilla 1.0
- dragdropupload 1.5.22
- FireFTP 0.94.6
- FlashGot 0.5.98.070302
- Google Images Re-Linker 0.4
- Greasemonkey 0.6.7.20070131.0
- LoremIpsum Content Generator 0.4.3
- MeasureIt 0.3.6
- Menu Editor 1.2.3
- MinimizeToTray 0.0.1.2006102615+
- MR Tech Local Install 5.3.2.3
- Remove It Permanently 1.0.6.3
- Stop Autoplay 0.4.3
- StumbleUpon 3.04
- Tab Mix Plus 0.3.5.2
- Talkback 2.0.0.3
- TimeTracker 1.2.2
- Torbutton 1.0.4
- TryAgain 2.0
Total Extensions: 24

Regarding your Context Menu, you should get the 'Menu Editor' extension (should be on my list)