The 1st thing I think you should do is add the doc type:
http://www.w3.org/QA/2002/04/valid-dtd-list.html . At the very least it should fix your centering issue.
Another thing I would strongly recommend is checking IE every time you would check Firefox, It saves a lot of headache later and makes problem solving way easier. One thing I might try to figure out your current problems is to copy your css file, in the active one delete most of it and start copying and pasting each section in until you know whats causing each problem.
and sorry I don’t know of anywhere that covers all known ie issues like that. Best thing I can think of is becoming familiar with both browsers.
Hope this helps.
