copper fittings

Hi there, I'm gathering together the knowhow and materials needed to change out the fittings under my kitchen sink. (They work fine, but the insurance company thinks they look too corroded) Wanted to make sure I had my ducks in a row from people who would know. The existing shut off valves...

I need to add some 3/4" copper pipe right after the 3/4" valve for all the water coming into my condominium. It is so that I have a length of pipe to wrap the conductors for a water descaler around before the pipe branches into multiple directions. It is going to require a number of 90° elbows...