Well, you certainly have a LOT of options now, wouldn't you say?
I think track wash for the tracks, then a combination of the other products for the rest. Actually, your tank is like the freaking ideal scenario for weathering. First of all, the scheme lends itself very well to weathering; and secondly, you are not constrained at all by any fluff-related limits on what would be appropriate - you can literally do whatever you want with it.
As for airbrushing, you are too modest. I can see from the pics that you are clearly better at it than me. I am using a 0.5 mm needle, though, which is like a fire hose compared to yours. For varnishing and enamels, I have a 0.7 actually. So if you're not getting too many clogs, keep doing what you're doing!