2012 1.8L coolant-related question

Have had a 2012 LS for nearly 5 years and have been pretty happy with it. A few months ago, I had popped the hood and noticed the coolant reservoir looked low...like maybe 1/4 inch above the lower hose connection. Mentally said I should pick up some dexcool and add some in. Unfortunately, I forgot about it 10 minutes later. Yesterday, after washing the car, I popped the hood and noticed the coolant reservoir was pretty much empty....just a slight layer on the bottom of it. Oops. So I went out and bought a jug of dexcool and added some in. 2 questions : 1. I had heard about the "antifreeze smell" problem with the 2011's (and 2012's?), but have never experienced that myself. I also don't have any signs of coolant leaks on my driveway and I park in the same spot everyday. Is it normal/possible for some coolant to perhaps evaporate out of the system over time, necessitating some to be replaced now and then? Or is it possible that it's leaking slowly somewhere, but maybe only while say driving at high speed, so that you wouldn't see any drips/puddles form on the driveway when it's just parked there? 2. I also heard about issues with bad (leaking) water pumps, but I think that was only with the 1.4L engines.....true? or does the 1.8 suffer from the same problem? Thanks for any input.