When I moved into this house the hot water heater (3 years old now, gas unit) was hooked up to the existing system with copper fittings. The whole house has copper supply lines.
1. Should I put dielectric fittings between the hot water heater and the copper lines? I know the dissimilar metals will cause the metals to corode faster.

2. Can I use brass fittings between the hot water tank and the copper pipes instead of the dielectric unions?