I'm glad to know people are still reading my old article about the South Korean AmVeh car!
No, ammonia wouldn't react with gasoline or ethanol, as far as I'm aware. Yes, it would burn as a fuel. Ammonia is hard to combust, so to reap the benefits of its high 120 octane rating, you'd need to make certain engine adjustments. Also, you'd need to make sure no copper/zinc/brass alloys were in use anywhere the ammonia is - it'll corrode those very quickly and that would not be good.
Using ammonia as a drop-in fuel is a totally different idea to using ethanol as a drop-in fuel. Different motivations, different results. The idea with ammonia is that, if/when produced from renewable feedstock, it is a carbon-free, energy-dense liquid fuel. If you don't think carbon is a problem, you won't think ammonia fuel is a good idea.
For actual engine performance using a gasoline-ethanol-ammonia blend, see this presentation: https://nh3fuel.files.wordpress.com/2014/10/nh3fa-2014-shehan-haputhanthri_1.pdf. See pages 13 and on: dynamometer tests demonstrating horsepower/RPM for various % ethanol blends; note the ethanol is used here as an emulsifier as well as a fuel, to stabilize the gasoline-ammonia blend. The same team of researchers at Texas Tech have published other work on the subject but I don't have my hands on their most recent publications, although I know they've continued to develop the work.
Regarding NOx emissions, ammonia is the reagent used in most SCR clean-up systems, so it's an onboard solution to its own problem, just takes a bit of engineering design to address.
For those interested, the actual application of ammonia as a fuel is more likely to begin in stationary generation (and certainly not in the US). Here's an article I wrote earlier this week regarding two utility-scale demonstrations of low(er)-carbon power generation in Japan: both employ ammonia in a dual-fuel combustion process, one in a coal plant the other in a natural gas plant: http://www.ammoniaenergy.org/industrial-demonstrations-of-ammonia-fuel-in-japan/