Could someone confirm that children 12 and under get into the Colosseum and other museums (except the Vatican) for free so that they do not need to purchase a Roma Pass? Also, if they get in for free, they would obviously need a metro card/bus card for public transportation, correct?
No, you don't need to purchase a Roma Pass for them but you will need to pick up free children's tickets for them at the desk at the Colosseum (after you all pass through security and enter with your adult Roma Passes).
The Borghese requires pre-reservations for ALL of you even if using the Roma Pass, and you should do that over the phone if that one is on your list. See the Roma Pass FAQ for instructions.
Only under age 10 ride Rome transport for free. If your children are 10 or over, they will need tickets or passes for the buses, metro, trams, etc. Rome is a terrific city to walk, though, and I highly advise trying to see as much of it on your feet as possible! We've only felt the need to hop transit a couple of times over our visits, and I've bought a few single-ride BIT tickets on arrival day and tucked them away for such occasions. Those also come in packets of 10.
If not already aware, it's good to know that the Roma Pass doesn't cover transport to or from the airports. :O)
Thanks for the helpful info. Would a 12 yr. old like the Borghese? Would the National Museum be "better"? Thoughts?
You probably know this, but what they would like depends on the 12 year old. Some would enjoy it, and others would rather die.