Auto blog setup questions - C-Class IPs, etc

Hey guys,

so far I have bought 5 C-class IP hosting at seo host, and I have auto content ready to go for around 400 different niche blogs.

I am really just wondering what is the most auto blogs I should have on one domain?

I am thinking of putting around 75 on each domain, with each domain on a seperate IP, is this good?

In the past when I was testing this concept, I simply used 1 domain on 1 ip, and put all the different blogs in subfolders ie:

mysite.com/horses
mysite.com/bowling
mysite.com/cathurling

and this seemed to work fine, although I only had tested with under 10 blogs so far.

So my main 2 questions summed up are:

1. how many auto blogs should I have on each domain?
2. should I have them in subfolders like I did before, or should I have
them on subdomains?

oh and 1 more question, just while im here:
3. Can anyone sell me some generic sounding name domains, that have
current indexing?

If you guys could help me out here, that would be great. I am sure i am not the only "autoblogger" in here
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