Time for new water heater

I'll be replacing my water heater next weekend and have a couple of questions.
First is, do I need to keep the existing expansion tank or is it safe to go without it?
Second, there is PVC pipe from the wall to the tank. Is there a fitting that will allow me to connect stainless steel braided lines from the tank to the PVC at the wall? I would probably change the shut off valve to a lever type while I'm at it.
Thanks!

Post some pictures

An internet search came up with this from Home Depot called the Sharkbite. It says it's push to fit on to PVC. This would not allow for the expansion tank.

Yes, you need the expansion tank. I would replace the tank instead of reusing the old one. And I would not re install like it is, if the tank becomes water logged the weight could snap the CPVC pipe. I would use copper off of the top of the water heater to hold the tank up.

Roger that phishfood. Does the expansion tank need to be located above the water heater? Can it be placed on the wall or floor?