The phones may work to make calls but it is unlikey that the ringers on them would work. Old POTS phone lines have much higher voltage for ringer than you are likely to get from the Comcast line.
Rotary won't work for dialing either and you would need some sort of converter if such exist to convert it to tone dialing.
There is an item called DialGizmo that will make your old rotary phone work on a VOIP line. Just plug your phone into DialGizmo, then plug that into your modem. Thats all there is to it. You can check it out here: "dialgizmo.com" It wouldn't let me post the link. Good luck to you.
This is an old post, so you may not need help anymore. But if you do, I have a rotary phone with Comcast. It's worked for the past 2 years (just now having an issue with dialing out due to an upgrade with our modem). I don't know about the pay phone but you should be able to use the other. Just make sure you change the wiring for the ringer as most of the old phones were on a party line.