Help me with best hosting setup for SEO

Confused! First, I have done pretty well with what I have done over the past couple of years in my niche. But I'd like to maximize SEO even more. I have done what some people say you should NOT do -- I have several sites that all relate to the same niche... and there is linking between / among them to each other here and there... and several of the sites are hosted at Hostgator as add-on domains. Meaning that each site does not have a dedicated IP. But, my SEO has done pretty well.

I have a few other sites in the same niche that are at Godaddy, as Website Tonight sites. I understand that these are NOT dedicated IP addresses, as well. I think I have might have one more site hosted at Ipower, in the same niche.

I keep buying keyword rich domains. Some say that my strategy of building very small (even one page) sites is not as effective as building one site and making good pages for the various keyword phrases. But my little strategy has worked pretty well. It seems it would be a bit hard to get "legitimate" links in my niches. So, I have created my own "fake" links. Again, I have built my own little network with linking between / among them

So, I am wanting to get even better results for my keyword phrases. Questions...

1. Should each of my sites have a dedicated IP? I probably have 20 good keyword phrase domain names, most of which have a small site built already. Some, I have yet to build.

2. Or... should I just have one hosting account and hang all of the sites off that IP as add-on sites?

3. Or... what about having five hosts and have one hosting account at each host and hang four sites off one. 5 x 4 = 20 sites. Thinking that Hostgator and Ipower and Godaddy and etc. would have their own IP, so, I would at least have five IPs. Then again, I really don't know how these IP addresses work.

I would just like to do this right. Yet, I don't want to screw up what I have going already. I have my main site on Godaddy as a Website Tonight site and these do not have dedicated IP. If I were to buy a dedicated IP for that site, would it change anything with the search engines? Would it mess up any SEO I have achieved already?

I also keep reading about how SEO likes blogs. I could add or convert some of these sites to a Wordpress blog. Add a blog to the small site I have already built or just make the entire site a blog?

Thanks, I need advice.