What you're looking to do is very doable, but it would be much better if you had any way to hard wire the two systems to a network. Understand that there are some down-sides (minor IMO) in going to a cablecard ready solution:
1) If you're a fan of the TV Guide Channel, you don't get that anymore. Of course, there is the freely downloadable Electronic Program Guide (EPG). Normally, this guide is updated often enough to provide 14 days worth of upcoming programming data, but there are reports of occasional update failures. I think the least amount of programming data I've was 10 days, but I've seen reports of users having only six days of data.
2) There is no support for On-Demand programming from Comcast (or any cable company). On-Demand requires two way communications from the DVR/Set Top Box and the cable company. Cablecard ready devices (or the cablecards themselves) are only one way receivers.
As for your questions:
1) Any of the cablecard ready devices will work for you.
2) Only the Ceton InfiniTV4 (USB or PCI-E) has four tuners, but you can mix and match devices at will (each device will still need a cablecard from Comcast).
3) The TV in the bedroom is going to need some sort of media extender (or another PC). If you can somehow make this a hard-wired connection, the Ceton Echo is the newest extender available or if you have an XBox in the bedroom, you could use that as well.
One thing you should know. All programs recorded from Comcast (and I suspect all cable TV providers) are tagged with DRM restrictions. From what I know, there are three levels:
1) Copy-Freely: This means once the program is recorded, you can watch it, manipulate it, or move it to any other device.
2) Copy-Once: Unless I'm mistaken, this means that once the program is recorded, it can only be viewed on the system the did the recording. It cannot be manipulated in any way and *I believe* not viewed from any other system.
3) Copy-Never: Programs flagged this way cannot be recorded at all (never actually come across this).
4) This would depend on your setup. An extender, attached to the network, can be assigned an available tuner. With either of the Ceton devices, one tuner could be statically assigned to the extender. With any other cablecard device, the tuners are dynamically assigned as part of the network.
Just as an example, during football season, when I can multiple games of interest playing at the same time, I have one of my Ceton tuners assigned to this PC. The card is physically installed in my HTPC just a few feet away. I can play the main game live on the HTPC and at the same time, have the secondary game playing live on this PC. Of course, my PCs are hard wired to my home network.
5) I'm using an older style Microsoft Media Center Remote Control. If you look other remotes are available from companies like Hauppauge (recommended), Pinnacle, Adesso (I think), and even Rosewill. If you already have a Logitech Harmony Remote, that could be programmed to control your HTPC (DVR).
In all honestly, I can't say how well using a wireless connection would work in assigning a tuner to the bedroom PC. I live in a small apartment and cannot cut holes in walls either, but I did have the cable connection running from the living room to the bedroom. I purchased a DIY kit to swap the single coax cable pass-through to a dual coax cable/cat5 pass-through.
As for the system you want to use, the Core I7 system and 8GB of RAM is more than enough to do all that you're asking. I've done all that you're asking with my HTPC set up (listed below).
-Wolf sends