Our website (wwhsrobotics.tk) just got a renovation, and I used a cms this time. Is there anything that I should change?
I’d change the keywords for your site.
“Register now on mysite.com!”, the mysite.com part should be changed.
Other than that, it looks pretty good, nice job 
You might consider buying a “real” domain. $10 a year gives your site a significant boost in respect.
Also, the banner at the bottom isn’t really annoying, but I think the traffic you will get through it is very minimal.
Because a lot of stuff is denied for not registered users (or is it team members), what other features does the site have? Is the forum a XOOPS forum or an adapted one (IPB, phpBB2, etc)?
I agree on this point, or atleast use a better redirect service. www.shortURL.com is a really good service, and costs only, I think $10 at the most. It comes with a couple (atleast) good services. If you just want a redirection without a lot of information about your traffic, you can also get the free version (but it’s sort of a pain, because they changed how they did everything).
If you are looking for a decent (low cost) server, I think iPowerWeb is really good (it is from what I’ve heard anyways). Brinkster is also good if you can/want to use ASP.