First off back to the hobby and to this Forum.
Has many have already mentioned, Acrylics ARE a LOT easier when it comes to clean-up & to the chemical smells that are produced.
The Tamiya line of paints I have used the longest, and have found them the easiest to spray with. Their bottles seem to stay air tight better and longer than the other bottles out there. The prior comment about Tamiya drying faster when sprayed does hold true. I have found that Tamiya's paints also attract dust alot easier. Tamiya also thins nicely. My biggest complant about Tamiya is their paints require some extra work with the hand brush, and the colors don't mix well together to make a different color. That, and Tamiya seems to be the most expensive of the paints that I have access to at my LHS.
Model Master I have had difficulty with the colors themselves. The lighter colors (yellow, red, green, and some blues) tend to be a bit transparent if not painted on a primed surface. I have even had this problem with some of the reds over a primed surface. This just might be me. For airbrushing, I have found MM to be reliable, and easy to work with. Thier thinner and cleaner I have found to be pretty universal in use. MM color selection is the best of Acrylics.
Polly Scale is another line that I have recently started using. I have not had a chance to airbrush with any of this line (hope to as soon as I get my spray booth made). But for brush painting, I have great admiration for. Polly Scale I have found to be a pleasure to work with when using the brush as it spreads evenly, and I have very little 'brush lines' to deal with after the second stroke of the brush.
I'd recommend that you pick up a few bottles of each, and experiment on a scrap of plastic to see what you like. As far as 'mixing' Acrylics & Enamels, that is a personal thing as well. I personally don't like to do it, mainly due to the chemical orders from clean-up of the enamels. In fact, I probably use Acrylics about 90% of the time (again personal choice).