These paints do stink, that is for certain :-) I don't know what is in them but I have heard them described as synthetic lacquers. They are not to hot for plastic. I use them all the time. Most are semi gloss unless otherwise indicated. I believe their gloss sea blue is in fact 'gloss' .
You don't want to thin them with 110 thinner. You want to get Mr Color Leveling thinner. I love using these paints except for three things:
1) The smell
2) They have some minor adhesion issues (had areas life off when masked over with blue painters tap or Tamiya tampe so make sure you wash your parts before using so they are free of any body oils or mold release agents).
3) They don't brush paint very well (maybe someone knows how to get them to behave with a paint brush?)
What I do like about them is their color accuracy. They airbrush beautifully and dry fast. They don't go bad. If they start to dry up in the bottle you just add some leveling thinner, let them sit over night, then stir.
Also, you can thin them in the bottle and it will affect their self life (which seems infinite).