Try this guide too, by Tunnie, with good piccies:
http://www.omegaowners.com/forum/YaBB.pl?num=1225024176It has the part numbers for everything, but the gasket one will be different on yours, I think, as his guide is for the 2.2. (Certainly don't think the gasket I got for my 2.0 had that number). Most aspects of the process are the same.
With regard to the tube you've found, it isn't coming from the EGR valve (rusty looking thing, nearside rear of the cylinder head) is it? I don't remember it being 5" long, but there is a small diameter vac hose coming off that which doesn't go anywhere, and terminates in a round black plastic fitting. LHS of this pic:

If that is the one, I suppose it works as follows. The actual valve of the EGR is moved by a vacuum diapragm (the big round bit of the housing). The vac source is from the throttle body, and this is modulated by a solenoid valve (above the vac diaphragm). When this solenoid valve closes, isolating the vac source, some means of letting air back into the low pressure side of the diaphragm must exist or it wouldn't be able to move down again rapidly to close the actual exhaust gas valve. Or something.

This black plastic bit will be a basic filter, to prevent particulates getting into the vac system. And I've just realised that this must be what rustym95 was on about the other day in another thread, sorry mate!
