Magento

Sorry for the two question post....

I’m just digging into creating a theme for Magento and found this post:
http://www.magentocommerce.com/boards/viewthread/215/P45/#t4268

That’s going to help a TON.

First, if creating a new theme what can be cut out of Magento?  I’m mostly asking in terms of JavaScript and CSS.  Can it all go bye-bye and a theme created from scratch that has all of the functionality I want or that Magento can offer?  I guess I’m asking is there core functionality of Magento that requires the heavy and bloated JavaScript?

Second, I guess this is related.  Just how scalable is Magento?  It seems there is A LOT of work being done for every single page view.  The HUGE main.xml file is read every time, along with dozens of other files.  Now, I haven’t gotten into the caching feature so I don’t know how much that’s going to come into play.

Thanks,
Kevin