A New Build Using USB Flash Drives

I'm about to do a new build and I really want to go a bit different.
1st Drive would be Vista, Microsoft Office 2007 and Adobe Photoshop. I figure around a 16 GB Flash Drive should do. I plan on Locking the Drive so all writing would be forced to the onboard Drive.
2nd Drive would be for RAMBoost. 16-32 GB Flash Drive
3rd Drive would be for Gaming/Photoshop and would be a WD Velociraptor.
4th Drive would be setup for other Files.
Backing Up and any files I need on my Base Computer would be routed to my Home Server.

Questions:
Would I see substantial performance gains using basically a Hybrid SSD/HDD system?
Is it possiable to make a USB Flash Drive as your boot drive and if so how?
Would I be able to take this "OS in a Bottle" around with me and use it as my main OS when accessing other computers?

Plans are of course eliminating the bottlenecks in my system which is the slow access times created by the Hard Drives.
Creating a Desktop environment that doesn't change and I can carry with me to access other computers. This would increase my performance as the Desktop hard files to one specific type doesn't change unless I physically enable it to be changed.
My ultimate goal is to have a high Performance Base Computer that can load in under 10 seconds with a standardized OS that doesn't change from machine to machine.

Thoughts, links to information, and suggestions are welcome.