so i assume you want one bowl left of where the existing one is and one right of it? if so, you should take out that angled drain and put in a normal straight out pipe for the left bowl, then probably the best bet would be to copy what you see in the basement and bring another drain line up where you want the new right bowl. this way you reduce the holes in the 2x3 studs, and you have easy access, so might as well. above that, you'll have to take the vent off the top of the new line up and over through the studs to tie into the existing line, unless there's some better solution that i can't see higher above the picture. Often it is easier to take the vent up into the ceiling and then over to tie in to the existing line, but I can't see that.
if the water lines are in a location that won't be in the way, you can simply buy a splitter to put on the top of each supply, and run a longer set of braided stainless supply lines from each side of each splitter to each sink. If you're comfortable soldering, I'd take advantage of your easy access and put in a new set of supply lines under each sink. Also, i'd move the supply lines into the wall cavity rather than bringing them up through the floor... take them about 20" up inside the wall and turn them 90 degrees through the wall and put the shutoffs there. much cleaner install and leaves floor of your cabinets free.