how to connect iMAC thunderbolt port to a cable TV set top box?

I am moving to a house that will have combination TV-phone-Internet services delivered via cable (Optimum is the provider). I understand that with my new iMac which has a "thunderbolt" port that I can use the iMac as a tv monitor and DVR (recorder) and watch live TV or recorded TV. I think it is possible to record TV shows either on the iMac's hard drive or the Optimum DVR. Beyond that, I get confused because I do not understand the details of RCA cables, coaxial cables, HDMI connectors, etc. Apple does not provide support for set top boxes (I called Apple), and Optimum does not provide support for Macs (I called them too). Since Apple is the party advertising the capability of watching TV on a Mac, I would think the burden is more on them to explain how that works, and maybe they have done so on their web sites, but I cannot find it so far. I can understand that the cable company does not want to tell people how to bypass the need for their DVR equipment. Before I go out and hire a consultant for a few hundred dollars to explain it, I was hoping I might find online some tips on how to set up a system at home. No luck so far.

Am I correct in assuming that wireless connections are NOT an option because a TV signal has too much bandwidth to work wirelessly? (I do have a wireless router already.)

If so and if I am using wires to connect the iMac, am I correct to think I want to use the thunderbolt port for best results?

If so, what next? What exactly is the adapter or cable I need and how do I plug it into the set top box? There are several people in the household, and so I would want the flat screen TV monitor to work normally at times rather than only use the iMac. Does that require several set top boxes? I would think that this would be an issue for many people, and it seems to me that this forum would be an ideal place to get help. So far the people I have spoken with say "well it depends on what you want to do and what your equipment is and for that you have to go ask ___________[someone else]"