It will be able to run the majority of Mac software for the next 6+ years, and probably every OS for the next 10 years
It will be just as fast as it is now...ie v fast
No you won't, it will last a good 6+ years if u want it too
Yes. When Apple releases the OSX/x86 machines, a special cellular-internet receiver in the G5 will pick up a signal from Apple in Cupertino and instantly render the G5 motherboard inoperable, forcing you to buy a new machine.
First of all, this has been discussed to death here already. With allowances for being a new member, please try the "search" function or scroll through the posts to see the previous posts before opening a new thread.