Question re ip address & page extensions

[dcg]

Hi There
2 questions:
1. Does having a single IP address dedicated to a site provide an advantage in terms of SEO over a site having an ip address that is shared among many sites?
2. I have a dynamic/db driven site and my plan is to create cached pages so I dont have to pass variables in the url. Idea is to make them easier for spiders to find and index. When doing this is it important to make the extension .html? If you compare the following urls does one have an advantage over the other in terms of seo?
link 1: www.website.com/widgets
link 2: www.website.com/widgets.html

[shilly]

1. I would not want any of my sites sharing IP's especially if I do not know the other Isites. You can end up sharing ips with a site that is penalized or banned in one or more of the engines. Your site will be associated with that site.

2. I am not 100% sure about this one, but I would think either would be ok.