WP Robot: hosting/keyword/newbie questions...

Hello everyone,

Apologies if these are simple questions! I've never tried autoblogging before, so please bear with me. I had a look today at WP Robot; it sounds very interesting.

There are some things I'm not clear about:

-Domain names: Is it advisable to have a different .com/.org/.info at the end of each blog? Or can I get away with using the free Wordpress blogs?

Would doing the latter (merely using free Wordpress) be detrimental to legitimacy or traffic of the blog? (I know some people will question the legitimacy of any autoblog, but please, let's not go there right now... )

-Hosting: What's a good service to use (if I were to buy my own domain names rather than using free Wordpress blogs) that can give me hosting for numerous domains under one account at a good price? I can't afford, say, 7 dollars a month hosting per site if I created 20 autoblogs...

-Extensions: Do would they have to be .com? Or would the cheap .info suffice?

-Keywords and niches: What's the best way to choose a niche and keywords for autoblogs? Should I base them around high priced, popular Amazon products which would be sold through said blogs?

If so, would it simply be a matter of seeing what sells well, for good money, on Amazon, and using the Google keyword tool to see if such products have a high number of global monthly searches?

Or am I missing some key things, here? I really don't have a clear understanding of keyword research and keyword selection...

-Finally, promotion of blogs: Is it worth linking to blogs using articles, document sharing sites and furthering traffic with backlinking/social bookmarking services/Angela's Packets?

Thanks for any suggestions!