I’m not really an expert in this area, but I think I can answer at least a few of your questions.
As far as speed goes, I think there are three main factors to consider: bandwidth, latency, and load (how many people in your area are also using the service.) Bandwidth is basically a measure of sheer speed, how many Mbits/sec you can send or receive data. Latency is how long it takes the modem to initiate the transfer of data once it is requested.
Cable, as far as I know, has high bandwidth but high latency as well. Thus, it will take a little longer to initiate a download or upload, but once it’s started it will go considerable faster. On the other hand, DSL has slightly lower bandwidth and latency, so transfers will start faster but go slower.
Cable performance can also suffer greatly if several people in your neighborhood are using the same service as you. This lag can be particularly noticeable during peak usage times, but in general isn’t severe enough to worry about.
In the end, I’d basically recommend going with whichever is cheaper, although being a TWC customer I can honestly say I haven’t been at all dissappointed with RoadRunner’s performance. 
As for routers and such, the main difference is this: a hub needs to constantly be connected to a “host” computer for the network to operate, so if you have a spare computer laying around that you wouldn’t mind leaving on 24/7, a hub could save you considerable money. All in all, though, I’d recommend getting a router instead. They are considerably faster, don’t need a host computer like a hub, and often come with loads of other features such as built-in firewalls.
Oh, and as far as having TWC split the connection for you…well they will, but you’ll have to pay an extra $20-30 per month. In the end it’s much cheaper just to get a router and do it yourself, and ahem have it discretely placed so the installation tech won’t see it and start asking questions. 