Name of the gutter stuff

At the sinks and toilet supply there a few different types of valves, attaching to 1/2 rigid copper. I have seen at the big box stores pipe threaded, sweat fitting, multi turn, or 1/4 turn ball valve all to compresion fitting. My initial though was a sweat fitting 1/4 turn would be cool but I am now trying to over think which one would be best. Any thought or preferences?

I'm installing a new vanity top for two sinks where there was previously just one. The old one was in the middle, so the drain will now be between the two new sinks. The sink centers are 34 inches apart. What's the best way to handle the drains? Should I try and use one J-bend in the middle with drains from the sinks meeting in a T just above the J? How firm is the 30-inch sink-separation rule I've read about? Should I instead install two J-bends and then feed the single drain line? As long as both sinks aren't draining simultaneously, will I have any venting problems either way I do this? Thanks for your guidance on this! PS: T's on the supply lines, or separate cutoff valves??