Having used the printout PREMs tickets several times, i can confirm a couple of things:
You don't need to validate your printed out ticket, it's only the standard SNCF-issued tickets with the magnetic strip that need to be validated. If you slotted your ticket into one of the machines, nothing would happen anyway.

However, you must make sure you have some form of photo ID with you when you travel, as you may be asked for it when your ticket is checked (indeed, the ticket's not valid without it). I wouldn't cut anything up, just fold up the page and take it with you as is.Imagine if you cut off something important and rendered your ticket void!!

When you arrive at Perrache, unless you have a lot of bulky luggage, it's probably not worth taking a taxi to La Residence, which is on a pedestrian street anyway. It's only one stop on the metro - you get off at Ampère-Victor Hugo and the hotel's about 50 yards up the street.