has anybody had problems with the wire harness being so old it fails from wrenching??  common areas?

Where the harness bend from the inner fender to the manifold near the clamp.

also i want to clean the egr as i have just hot tanked a new manifold and i want everything squaky clean inside!

If it works then clean it up & reuse it, I have & might just past smog emissions here in Cali.

knock sensor. is ther any specific tourqe?

Snug it down with a wrench, no torque, just tight.

reuse the old copper washers on the fuel rail banjos?  

The head gasket kit should come with new washers. I have installed new washers & they leaked. I have had to reuse the old ones so it would stop leaking.