Victaulic makes a dielectric fitting that could solve your issue.

No

No

Dielectric union

Yes and no. Pipes are pipes and many houses have both copper and galvinized. But copper and galvinized pipe must never come into direct contact with each other. You have to put what's called a dielectric fitting (available at your local hardware store) in between them. The problem is that without a dielectric fitting you'll get what's called electrolysis. Electrolysis eats holes in your pipes. Like I said, just put in a dielectric fitting. No sweat.