I run a Web Server on my connection and I can verify that it is OK to do so as long as its not a profit making website and it doesnt attract too much attention (I get about 1000 page hits a day and NTL have never made a fuss).
NTL do not block any ports as far as I know. EDIT: Just read the post above. They do block some ports but none to do with web hosting.
VPN is fine.
If you go over 75GB you get dropped to the 512Kbps service for the remainder of the month.
My connection has got a 99% uptime so far since I started running my Web Server 6 months ago.
The speeds are 10Mbps down (about 1200KB/s) and 512Kbps up (about 60KB/s). If NTL get their act together you should get these speeds.
Ive run VOIP before and Ive found it fine with up to 4 people at a time on Skype.
Its 34.99 now. 37.99 was the old price.
If you need any help setting up a server at home, let me know and Ill be happy to help. If you have MSN, add msn (at) abyssunderground.co.uk and I can help on there. My website is dedicated to helping set up servers at home as well so take a look if you get stuck.
Hope this helps.
PS: My Call is 2E0EZW