If you want to know ALL about web hosting, domain names, etc, I think taking a class in this area would be the most beneficial to you, since we can't possibly cover everything in one conversaton.

But anyway, a good place to start...

Glossary of Web Hosting Terminology
* http://www.thewhir.com/find/web-hosts/articles/glossary.cfm

How to choose a good domain name
* http://www.stir.ca/webtips/website_domain_names.html

And about the semi-professional design... well, it depends on how much experience you have but one easy thing to remember: keep it simple! Pick two/three colors, decide on a basic layout, and from there on keep it simple and consistent.

Here is a website I designed for the business department of a school... it's a very simple website, and they have changed minor things over the last three 3 years, but the main design is still intact.... why? Because it's so simple. http://parkwaysouth.net/

If you have any more specific questions, feel free to come back!

Hope this helps.