How far up do the '<H#>' tags go? Is it limited or unlimited? Also does putting to many '<H#>' tags have an adverse effect on search engine rankings? I wanted to use H1 to H5 on my index page but I want to be sure I do not get penalized.
There are only 6. There should be only one h1 per page, but the others are pretty much unlimited, but they should make sense. Googlies don't count the number of <H?> you have and generally doesn't care. Headers can help with SEO by pointing what parts of the page are most important (to people searching for stuff). So if you have a page about raptor-riding banditos in Utah who are having a BBQ this weekend, the raptor-riding banditos part should be more important than Utah or the BBQ which is only a part of the page. People searching for Utah alone or BBQ's alone shouldn't find your page coming up near the top as they are not searching for raptor-riding banditos.