Mac problems. Is CSS the culprit? JS?

I am building a site for a photojournalist friend. It works fine on the PC in IE 5, 5.5, 6 for PC (I have not tested netscape yet but it isn't a priority).

But, I'm having three problems on the Mac:

1) the site gets utterly whacked in IE 5.0 (and possibly other versions) for OS9 (css issues?).

2) In OS X, Safari does not properly render captions (#ss_text) and slide numbers (#ss_counter) and previous/next button navigation. (css? javascript?)

3) Also in OS X, IE 5.2 has one little problem--busting out a bar from the right edge of the page, thereby extending the horizontal scroll way out. (css issue?)

I'm no expert and my patchwork code may not be entirely elegant, but I'd really like to make this site work for a friend of mine, and would immensely grateful for any help...

An example page with captions would be: URL

My CSS is here: URL

The js file is here: URL

Would it be better to paste stuff here? There's just a lot of it.

thank you!