This may be asking for a lot, but I'm looking for some detailed info about the pros & cons of "Self-hosting" a website and Email system (on site at small business) vs. using a "Web Hosting Service". I have found some brief and generalized articles. The one on this site (http://www.webhostdir.com/guides/hostevaluation/) is pretty good. But I'm looking for even more detailed info/scenario's about the topics listed in this article and in relation to things such as:

Server hardware and software costs.
Server hardware and software set up.
Server hardware and software support.
Server hardware and software upgrades.
Email Server hardware and software costs.
Email Server hardware and software set up.
Email Server hardware and software support.
Email Server hardware and software upgrades.
Server back-up system costs.

The company has approx. 12 employees. The site would be mostly informational data (15-25 pages) with some desire to offer video streaming and light Ecommerce traffic.

Thank you for any further insights you can provide.

You nailed it very well. All those issues are valid. Basically, all the issues of running a server 24/7/365 plus upgrades and maintenance.

Regardless of how small or "informational" the company's site is seen as being today I guarantee the first time a customer complains that the site is slow or was down, or the CEO can't get on to the site from home, your butt will be in a sling! It won't matter how small the company or how minor the problem you'll still be in the hot seat.

Go for a virtual dedicated server at a good company if you need much resources.