[G4] newer os/faster processsor and i tunes question

[dapper dan]

i am running mac os 10.2.8 on my 867 powerbook g4.can i put a newer os on my 
hard drive and what is the cost of this and where do i purchase it?i would 
like to run something as new as possible since i want to run pro tools mbox 
onto the book.

also,i s there anything complicated about dumping my itunes music collection 
onto an external portable hard drive?

and finally,is it possible and worthwhile moneywise to install a faster 
processor in my book or better to just look toward buying a new one?

thanx much
happy holidaze
dan