Connections are either "Incoming" or "Otbound".

I have several questions on this:

What is the difference between these two?
Why does LimeWire not allow me, unlike other Gnutella apps, to disallow incoming connections?
Why am i only getting incoming connections (6 of 6 or sometimes 5 of 6 connections)?
What would be the best setting for ADSL modems?

As far as I understand my ADSL connection is limited to 512kbps downstream and 64kbps upstream. I would like to use these as effectively as possible. With 5 to 6 inbound connections and sometimes 1 outbound, after 5 minutes or so I have a 'stable' 2TB available. This is not exactly an awful lot, certainly not the 24-27TB I've seen on other people's machines.

Other info:
System: Win98SE, LimeWire 1.7c
Modem: Alcatel SpeedTouch Home (ISDN) tweaked to a Pro

Off topic: How does upload speed affect downloadspeed?