Thanks, this answers a lot of my questions - hadn't occurred to me that I could use the two DVRs together (although I suspect I'm going to run into a problem with a lack of HDMI inputs on the receiver). Thanks also for the confirmation of no-customer-owned eMTAs - looks like it'll be the 6141 and possibly a dedicated router (Newegg currently has a great price on the 6141 and a free router deal until 8/22, so I may look at that, despite "vaguely specified router" probably meaning "really cheap and nasty router").
I think i've figured out the splitter stuff for myself - assuming I have to go with a 3-way split (or a 4-way split with the two DVR setup) it looks like as long as I can keep things so that the cable modem only gets a single -3.5Db signal drop it should be OK. It'll mean the other connection have either a -7Db drop or a -10.5Db drop (I think) unless I go with a 4-way which'd just give everything a -7Db drop.
Personally, I don't really care about any of it except the internet and the phone, but my spouse insists we keep the TV