1) You can use the cheaper sanke tap either way! Just like faucets/shanks, the chrome plating is usually fine under regular use, the all stainless is bombproof though.
2) I find that putting my couplers in the "open" position (lever down), removing the beer nuts/washers/check valve, and soaking them in oxi clean then hot water is plenty to clean even a gunked up one that's been hooked up to a keg for months. I'd guess a good rinse in hot water (you should be able to see the water come out the top port) followed by a spritz of star san would be fine for your light use. If you can still smell beer when you stick your nose in there, give it a soak.
Remember to hit the rubber parts with keg lube!