With stock suspension you can run a 33" tire and wheel combo but you may get some rubbing when you make a U-turn or when you are flexed up on the trail. A simple mini lift/ leveling kit like the Daystar one you linked would be a great addition. Tereflex also makes a simple leveling kit that would work great. (We sell them on our ebay store if you are interested).
As for your gears, 3.73's are fine for a 33" tire. Your 2012 has plenty of power for that set up. When you are ready to upgrade to a 35"+ tire thats when you'll want to look into better gears.
Generally speaking, 16" wheels and tires will weight less than 17" wheels and tires but it may depend on the tire and wheel combo you select.
Let us know if we can help you more. Call TC at 1.888.459.4080 ext 51826 if you want to talk about the fitment and wheel and tire options with another JK owner. TC has a 2012 JKU and knows Jeep fitments well.