You braze copper with a copper brazing rod. It does require a certain amount of skill and practice.
you solder or braze it
carefully
it is not easy to weld hard materials....it always difficult to hard materials.....
I am interested in the answer to the posed question, can you cad weld re bar to copper ground wire? If you can do you protect the dissimilar metals with No-ox or some other treatment? No treatment of the copper cable to rebar in necessary after the exothermic weld is complete (Cadweld). Just pour concrete.
yes
JB Weld
Yes, the compression fittings designed for copper work on both soft and hard copper pipes.
tig or mig depending on the wall thicknessCopper to copper is either soft soldered, or silver solderedSilver solder is a bad term as "solder" normally means lead content according to the AWS
lead is soft and copper is hard
Because copper is very hard and does not get damaged.
No, copper pipes need to either be soldered, or connected with compression fittings. PVC cement will not bond with copper and provide a "solvent weld", it would be a very weak connection.
No, hard copper pipe will split when you try to flare it.