A pipe cutter is the best tool to cut PVC pipe.
Yes, if it is rigid PVC conduit approved for electrical installations. Don't use PVC water pipe as it will be rejected if inspected.
Ribbed, bendable steel pipe used on combustion engine exhaust system.
I think that as long as you use the paint use for the engine block
No, do not use glue. Use teflon tape or pipe dope on the threads. You should also make sure you always put the male PVC thread into the female metal thread. If you do it the other way you will tend to split the PVC fitting when you tighten the threads.
Exhaust
if your waste pipe is PVC and your glue is for PVC . yes! but make sure to use a primer(cleaner) on the pipe first.
Absolutely Not!
Use teflon tape with a little pipe dope. If you don't ever have to take apart again then you can use glue which you are calling cement
Lead wipe a brass nipple into the lead pipe and then use a female adapter x PVC on the brass threads
Yes, for proper bonding of PVC pipe and fittings. Primer also code requirement.
Exhaust