Originally Posted by newsblaze

When you generate the sitemap, check that all the URLs are unique.
In ecommerce sites, there is often more than one way to get to a product, with a different URL, so be sure that for any particular page of content, there is only one URL.

You won't have any problem with 4,000 pages in the sitemap, as Chandrika said, you can have 50,000.

LOL, if you think 4,000 is very large, what would you call mine with 640,000 ?

I generate my sitemap with custom software I wrote, that walks directory trees and manufactures the correct URLs. Some sitemap generators make HTTP requests that will be seen in your webserver logs.

Regarding HTML sitemap, 100 isn't a hard limit, but if you are using that for visitors to read, breaking up the list is a nice thing to do. The suggestion of grouping categories by Bagi and cbos is a good one.