The placing of a forum on to a page is possible as long as you stick to one or two guide line's, ( why u would want to is down to you ) People can still get to your forum direct or though google.

1/ use a iframe on your page wider than 800pix
2/ iframe must be scrollable
3/ don't use a skin that has a static banner wider then 800pix.
4/ don't let members post images wider than 400pix
5/ make sure that all exturnal links is set to open in new window.

A demo of this

Answer to your question two, find a suitable skin then change the header, which can usaually be found in the skins image folder.

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