SERVICE PAGES: Should I have a page for each of the services on my site?

Yes ideally have a page for each service of your site. I think about 8 pages is a good total.
How do you decide which services to feature?

Go with your most popular and the ones that make you most money.
Don’t split out pages too much, if you can’t think of a whole page of different content to write about the service, question whether it should exist at all.