Distance vs Attenuation vs Speed?

I'm moving into a property which has the option of ADSL at around 3Mbps (and no immediate plans for FTTC on this particular cabinet) or Virgin Cable. Although I really want to be with Plusnet, it looks like Virgin is the only sensible option.

I have a few questions:
1) I'm totally unfamiliar with DOCSIS. Is the line rate fixed, or is it adaptive as with DSL? If adaptive, what kind of losses do you get?
I'd like to locate the Superhub centrally, for maximum wi-fi coverage and ease of Ethernet cabling, but not if it's going to impact reliability or performance of the modem side.

2) How big is the external junction box? Do they provide smaller or larger junction boxes dependent upon what services you choose, or does everyone get the same?

3) How does the connection get made at the footpath tee? i.e. does the cable exit the back of the tee, or does it come out of the top?

Thanks for any advice.

Edited by deleted (Sun 11-Aug-13 12:17:49)

Virgin Media cable is a fixed rate service, in the sense that if you buy a 30 Mbps product it always connects at the 33 Mbps that Virgin provision at.

The variations in speed are down to contention.

On their current box sizes etc not seen a recent install for a long time so no idea if things have changed a lot.

In reply to a post by cdldt:

2) How big is the external junction box? Do they provide smaller or larger junction boxes dependent upon what services you choose, or does everyone get the same?

3) How does the connection get made at the footpath tee? i.e. does the cable exit the back of the tee, or does it come out of the top?

Thanks for any advice.

2) Everyone gets the same in a particular area, it's rectangular and a few inches high, about 2/3rds as wide.

3) Depends on your install, can be done either way.

Thank-you both for your replies.