Well, like Linda said, there's a lot of information to be shared to answer your questions, but I'll start with getting a site up.
My suggestion would be to have a site specifically for your product as opposed to a blog. Blogs are great, but if you're going to do PPC adverts, then I really think a regular web site would be a huge benefit. you could always add a blog in addition on the same server at no extra cost.
For example, if you're site will be relatively small, which I'm thinking it would, you could go with GoDaddy.com's economy package, make sure to sign up for linux hosting, and with that account you get a lot of extra add-ons to use if desired. One of those is Word Press blog -- great one. I just started my own and absolutely love it. (reminds me, I should post on there! lol)
As for creating a site, a lot depends on your skills in that area. That's a whole new issue...what are your current skill levels in creating a site?
I'll stop there for now...
