Yes. Like with any acrylic and especially craft acrylics you do need to prime the parts first if you want them to stick to plastic. The Testors craft paints despite the cheap looking bottle are decent paints. In terms of use they are like most any other craft paint. If you want a gloss finish you will need to clear coat.
I have a couple of different thinner recipies I use for airbrushing craft paints.
For brushing, water will do but sometimes I use one of my thinners. But for a nice job you should thin the paint some so they flow off a blush nice and lay down smoothly. I always use a iittle retarder and or flow aid. My thinners have them in them already, plain water of course does not. But many folks brush craft paints cut with just water.
Suggestion: Look up a guy named Barbetos Rex on you tube for his second video series on spraying craft paints if you want to airbrush craft acrylics. His first series was ok but he moved away from Winshield washer fluid in the second series.. The paints just apply a little easier not that the first doesn't work. I've been spraying acrylics and specifically craft paints for maybe 5-6 years now myself. Not always, I do use many different paints solvents and acrylics. So does he but he has reviewed more paints than I think anyone in the model world. Some folks don't care for his approach, I think he is fairly informative and gets the job done.