I feel completely inept and dumb, and several hours of the Googles have only sharpened my sense

I have Comcast high speed internet and their "basic cable" option (cheapest way to get their fastest internet).

I don't watch much tv, but am finding that there are a few shows on HBO and Comedy Central, e.g., that I would like to be able to watch.

Was looking at a used Tivo on local CL, but am feeling completely stupid:

a) If I got a Tivo and wanted to "tape" (that dates me, doesn't it?) a few shows, can I do that simply through a Tivo subscription or do I also have to subscribe to those shows on Comcast itself?

b) I see that Tivo wants (needs?) a phone line. I have VOIP (Ooma) and no phone line anywhere near the router/Ooma box.

Open to any other suggestions, given my modest DVR'ing needs