As for Google Adsense, you can insert just a single piece of code from google in to your Header Inserts, which will allow Google to place their ads around your pages wherever they feel is best. I am currently using this, and it seems to work out really well for me on the sites where I use it.
Okay, and by header inserts do you mean the custom header for each forum or the Header Includes section?
The "Header Insert For All Pages" section
For example, this is how you would add google ads tracking code to all pages:
note: use your own code where I have inserted XXX at