Hot Water Bath for Enamels?

yes.

Stir the paint & place the tin in a shallow container of hot water until the paint is warm, the same sort of thing you would do with an aerosol.

Yes, put some hot water from your tap into the pan and let them soak.

If you don't want to ruin the paint bottle labels then put some saran wrap over them and sit them in water that is only about 3/4 the height of the paint bottle.

You can also put the bottle under a 100 watt light bulb for several minutes as well. 

Put the airbrush under the light as well as there is no use putting 90 degree paint into a 60 degree or colder airbrush.

By the way, when I was reviewing somebody's modeling project, a claim was made, not tested by me yet, that thinning Tamiya acrylic paints with nitro thinner or acetone (not the special Tamiya thinner) results in extraodrinarily smooth finishes. This is supposed to be the newest fad.