DSL v Cable Internet Service

Hi, I am moving and considering switching to cable (Numericable) for both internet and TV. I have been with Belgacom for years without a problem, although not for TV. Am I right in believing cable is faster and needed for the TV component? I've read it may depend on who else in the neighbourhood is sharing the cable? Is there any way of finding out how many are sharing?

Also, can I keep my skynet email address, with just my GSM contract and no landline?