1) Go to Control Panel > Personalization - Panels.
You can remove Web and Contacts there, leaving only Application, but as andrewfblack suggested Personal Menu is a good choice as an alternative. You CAN use Applications only, but it is somewhat limited.

2) See above answer. Personally I have not had any real need to install another OS

3)Haven't heard either

4) Nokia SU-31 case, gotten a few weeks ago. Marvelous thing. Stylish and comfortable. I can certainly recommend it.