Definately get an airbrush - the finish of just about anything that's airbrushed is about 1000% better than hand brushing. I often run Automotive acrylic thinner through my airbrush at high pressure - I find that even after breaking the gun down that the acetone based stuff keeps the gun pretty clean, but disassembly and a proper clean is always a good idea. Soaking the bits in acetone softens any kind of paint and makes for an easy clean.
Properly reduced acrylics merely means "thinned". In some countries they use "reducers" instead of thinners (the same thing, though). It's just a matter of semantics.
You'll have to experiment with the amount of thinning required for your paint - different brands, and even different cololrs within those brands, can behave a little differently. There's no replacing experimentation and experience. No-one's born with it - the reason I have so much skill and knowledge is because of the huge number of mistakes I've made - I learn from my stupidity................ouch..............