You do not need dedicated ip's, but having them can be advantageous. For example if you want to send links from your own sites to each other. Using separate ips is recommended.
This is especially apparent if you are using some of your sites as support sites for a main/money site. Then you should always have dedicated ip's.
I've heard this too. Although, I've also heard that the available IPs will be a part of the same sub group, so it may not be of as much help, as say being from separate hosts.
I've heard this too. Although, I've also heard that the available IPs will be a part of the same sub group, so it may not be of as much help, as say being from separate hosts.
The only time you will run into a problem is when you link together all said 20 sites. Google will notice that the keywords don't relate and they will consider it a link pool.