You're going a little too fast for me!!!
To recap:
1-Will copper and alu corrode? How?
2- Supplier of copper in Canada?
3- Ideal placement of in/outlet on a home-made spiral block?
4- Ideal flow rate for system?
Answers:
1- Yes, it's called galvanic corrosion.
2- Don't know, but you can always go through DangerDen. Locally, I would try a machining shop (yellow pages)
3- Inlet in center.
4- Depends on overall system. Need more info!
