A/F - goes to O2 sensor (makes lots of colors, doesn't do shit but look pretty. I suggest you get rid of this gauge.)

Oil - get a brass T fitting where your oil dummy light sensor is (next to the oil filter), and tap it from that.

Water - depends, do you want radiator temperature, out of block temperature, into block temperature? You tap it differently depending on what your looking for. Easiest tap is the overflow screw on the coolant outlet pipe or from the side of the block (exhaust side), just remove and tap it from there.