WordPress as a CMS with multiple blogs

So I’m in the midst of transferring our website to WordPress blog and pages to use as a CMS and I’m having some troubles.

First of all, here’s our clan website:

https://www.ubermelons.com/

First problem: Formatting.

This is what the server info page should look like: https://www.ubermelons.com/serverinfo.html

But when put into a wordpress page, it turns into this: (look at the table)
https://www.ubermelons.com/?page_id=27

Could this be a problem with our .css? What I did was copy our css from https://www.ubermelons.com/?page_id=27 and just put it into the style.css for the theme that I made. I also added a couple comment things into the style.css to change the comment box size.

The roster page appears to be working fine:
https://www.ubermelons.com/?page_id=13
compared with
https://www.ubermelons.com/roster.html

Another issue is we’re wanting that header image to change for each page. How can we do that when header.php for wordpress is the same for all?

Last thing: Two “blogs” which we’ll be using for news and updates. One is the main page, run from https://www.ubermelons.com/wordpress. But a clan member will be running another one for league/tournament news and info. We’re wanting the style for the second blog to be the same as the front page, with a different header image, and different title (of course). How can we get this second blog to share users, header/sidebar/footer.php files, and all those things for easy updating?