Haven't painted models in a loooong time, some (stupid) questions

You'd probably want to paint solvent paints before water based.

Weathering includes drybrushing, but encompasses more than just drybrushing, such as washes, stains, paint chipping etc.

I like to drybrush with artists oils, the blend nicely and don't dry out too fast the way that enamels seem to. Just get a little paint on an old brush, wipe all of it off, then lightly brush it over the area you want to highlight. The left over paint will lightly stick to the raised details. It's a great effect after you've had a bit of practice.

Make a wash with water colors or artists oils or something similar, it's just way thinned down paint, so you don't want to use similar paints and washes, or the wash will eat your finish away. Load the thin paint into a fine brush and touch it to the base of raised detail areas and corners of panel lines, let capillary action carry it around the model. You can wipe any excess off.

Hope this helps some.

(1) I have a mix of solvent-based paints and water-based paints, which do I paint on the model first, or is it not safe to mix paint-types?
It’s never a good idea to paint solvent over water based because the solvent in the solvent based paints is “hot” and will likely eat through your water based layer. You can paint water based over almost anything, but be careful putting water based over water based because they can bleed into each other if not fully cured.

(2) Weathering...same as drybrushing?
Check this site out for some good weathering techniques
http://www.swannysmodels.com/Weathering.html

(3) How do you drybrush? Solvent-based paints only?
For dry brushing I always use a wide flat brush. Get a little paint on the brush and brush it, repeatedly, onto a napkin or other surface to remove almost all of the paint. This is important: When I mean almost all, I mean almost ALL – barely noticeable on the napkin or whatever you are using. Then, stroke the brush, (don’t dab) lightly over the raised pieces (such as the interior of a cockpit) to highlight the raised areas with paint. It may take several passes, each building a small amount of paint onto the raised surface. Try practicing by dry brushing the raised numbers on the kit sprue trees. When you get the technique perfect, you’ll be able to highlight just the raised numbers and nothing else. Don’t rush because too much paint will flood the piece and you’ll lose the effect.

You can dry brush with almost any paint, but oils dry really slow (days or weeks) Enamels dry faster (minutes) and Acrylics (water based) dry really fast (less than a minute). The slower the drying time, the easier it will be to control your application. Note: When I say “dry”, I mean “to the touch”. “Curing” is a longer process and is a chemical reaction over time rather than an evaporative process.

(4) other quick/simple tips on detailing a model is appreciated.
Always let your paint fully cure before messing with it again!

Good Luck!

Thank you kindly on the link and the tips, esp. the differences between the types of paint.

Cheers!