Direct Connect will definitely not work if you have some kind of firewall issue. It seems you're aware that if your ip address shows at the top of the DC search box then you're ok to go (so long as the other person doesn't have firewall issues either.)

Your answer to Q.13 about seeing the brick wall is a firewall issue of some kind. Yes it could be your software firewall, or your connection device or your isp at fault.

Actually your exact model of speedtouch may just be an important issue here as many adsl modems & routers have internal NAT firewalls.

Is your XP firewall on or off? Go to control panel & open the XP firewall control panel & make sure it's turned off.

I don't normally recommend this, but just for a short time, disable your Comodo Personal Firewall. Then re-open or restart LW & see if you still see the brick wall. If yes, then that probably means the problem is either the isp or speedtouch.