There is a big difference between a cable modem and a DSL modem. There are many types of both available and these options can be viewed on Amazon. A cable modem uses a coxial cable input to connect it. However, a DSL modem uses a phone cord in order to function.
If you are spliting your own cable in your own home, electronic supply stores sell a cable spliter. If you split the signal too many times, it degrades, and you will have to contact the cable company to have your signal boosted. However, depending on the provider, you may be charged for additional connections. Service from basic cable is controlled by the tuner of your TV or cable box. Spliting a signal after a digital tuner will produce the same channel on every TV after the split.
3
3
Zero
3
3
1
zero
Never
25
The Feb 2011 was the only split in the last seven years I think.