Two questions about affiliate links - displaying images via js and detecting country

I wasn't sure whether to create two threads or ask two questions about the same subject in one. What's the better course for the future?

1)
When my large ad rectangle is AdSense, Google most likely doesn't care because 1) AdSense is Google and 2) The ad is shown via javascript, which spiders supposedly can't see.

However, where I have opted to remove the large image ad in favor of an affiliate graphic, might I see a penalty since the graphic is now a regular old image file and link appearing on every page for guests?

Should I use javascript's document.write to display the ad and link for visitors so that they see it and (theoretically) search engines don't?

Or does it make no difference?

2)
I realize that the affiliate I am trying to promote doesn't ship to/service all countries. I would like to make it so that the ad only displays to people in the US and good old AdSense displays its poor performing ad otherwise.

Is there a way to detect what country a visitor is from and display something appropriately, short of spending hundreds and hundreds of dollars for an ip to location database?

I thought that perhaps since I'm only looking only for country there might be something easy/free I can do programatically...

Thank you!

Look into running openX or another ad management software. It will handel your geo-target and your display as script issue all in one shot.

Thanks, Brian. I'm not excited about adding yet another layer of... stuff, as I don't know how or if it will work with ad networks down the line, etc., but I think both issues are important so I'll definitely be looking into openX.