Where do you enter Penn Station for Amtrak trains?

All entrances will lead you to Amtrak. 7th avenuenear 33 street might be quicker

8th Avenue is fastest but all doors will get you there if you follow the signs

You cant

Any entrance will get you there, they have a large waiting area hard to miss, just look for the signs or ask a cop.

8th avenue, but any entrance will get you there eventually.

Any entrance and you will find signs. 8th Avenue side is closer if I recall correctly

Sorry