The idea is to have consistent header contents (aka logo and homepage link) but then some random images. So the only changing HTML will be the number of DIV tags inside the header DIV tag with varying classes to set the image that will be placed in the DIVs and where it will be positioned. Would this changing content on every refresh of the same page for instance, affect SEO? I had given it no thought but then a colleague kicked up a fuss. I know it's not a precise science but I think I can trust your collective opinions.
google won't penalize you for things like that. they are really after people who "cloak" to try to take advantage of the spider. they have certain things they are looking for and you should be okay.
perhaps that won't affect your website. Google does not penalize a site for reasons pertaining to that, not unless you perform black hat techniques.
I don't think so, come to think of it bots can crawl those contents and I can't see any reason why you get penalize and you are not even doing black hat technique on that.