Get water cooling if you really want it, but it's usually quite expensive. I guess you would be getting a pre-built water cooler such as an H80 or H100, as opposed to building a water cooling system yourself.
I don't really know much about touch screens, but tbh i'd rather just get a good quality monitor for playing games
You probably won't need a sound card as the motherboard's on-board sound should be good enough
I don't know when the sales will stop, as I hadn't even noticed that there were any sales