Whoa Ash, didn't realize I wrote a book. Sometimes I ramble, but I think there's probably some good advice in there somewhere.
As far as where to send forum sig and blog post visitors. I admin it didn't really look at site much, so giving somewhat blind advice. HOWEVER most homepages have lots of nav links and are trying to show a vast array of what they offer. Fine for search engines.
But if you are doing TARGETED forum or blog marketing
you know who your visitor is, so it's good to either send them to a category page (if that fits for you) or a category specific landing page.
Think of your site like a giant mall and lead them where you want them to go, to take the action you want them to take. If they just walk in the front entrance to the mall and can't find the store they want OR it's at the other end, you could lose them before they buy. If they called your mall and asked if you had any music stores, you would help them get directly to that store, right?
You also want to minimize the # of clicks it takes them to get there. Realize if they have to try to figure out how to get where they want to go and also realize every extra click they have to make - you run the risk of them getting lost or interrupted and then they never make it to the buy button.
So if you want to focus on music forums and blogs then your anchor link would say "Best Music Music CD Prices Here" (or whatever) and link to your music CD page. If you are on a Rock forum, then send don't send them to the cat page send them directly to your Rock section.
That does a couple things! It gets the eyeballs that see your sig direct to the part of site you think they'll be interested in PLUS it gives you targeted KW link juice to that internal category page - which in turn could help you get higher ranking for that cat or product specific page.
Make sense???