I would like to suggest you that using percentage and pixel both,will make complicatipns, you can set specific pixel width to all ur header and body to avoid your first problem, you had better to choose 970 - 974px as width.
some of the following works will to reduce the weight of the above problem.
My second problem would be the HTML optimization. Some pages are hard to load.
1. You are using 9 style sheets in your webpage to reduce http requests you must make 3-4 style sheets into a single one as the same way total as 2 or 3 instead of 9 documents, also try to minify the size of style sheets.
2. Images you used are bigger in size it takes time to load in small internet connections. Nothing to do with that,,
3. Also try to minify the source code of your website.
FYI .. The meta content is not properly written on the web page.
You will know the truth, and the truth will set you free (John 8:32)(The truth is about the only begotten son of GOD.....When you feel you are alone for facing your problems, God will never leave you by your own You are important for God