Questions on plugins, categories, Nav Bar, FCG, Plugins

[Tech Support]

I am gradually moving my website to wordpress and I do have 3 major questions.
http://www.businesswithoutboundaries.net

I don't know what I did but so many things are going wrong at the same time;

1. Pages in Admin Area are not displaying for any editing or modification.

2. Plugin page to activate or deactive installed plugins is not showing.

3. My FCG is no longer working and showing my pictures as it use to do. I can't figure out, what went wrong.

4.All Categories in my blog page are not showing but giving an error message.
"404 Bad Request"

5. I have lots of pages on the Nav Bar (Menu), how can I make the bottom 2 rows of Nav Bar( with white background) have a black background like the top Nav Bar.


Thanks in advance for you help.