[Nadia]

2) Is there any way to use appropriate custom skins for stationary aircraft? I would like the planes I place on a field as static objects to look like they belong to the same squadron or group as the player aircraft.

YES. But these are DEFAULTS skins. Each aircraft has at least one, quite often two, sometimes even four or more defaults skins.
One of them is called summer ( MOST COMMON EXEMPLE ).
A default skin mod for it may look like this:

MODS/Any NAME you like/3DO/plane/Exact NAME of aircraft/summer/
skin1o.tga
skin1o.tgb
skin1p.tga
skin1q.tga

To transform a regular skin in a default FORMAT you..

1- apply desired skin to desired plane in QBM. [ SELECT also proper Side+Country+Map ]. Play a bit. Stop-Exit back to QBM.
2- get the new format of the skin, which is now in paintschemes/cache.
3- make mod with it.

A- to access, go to this cache, while game is running; use computer start/stop key, usually this is key with Microsoft Logo ( little flag ), and explore into cache file. Copy.
B- OR change Clear Cache setting in conf.ini temporarily: 1 to 0; stop game normally and this cache is not cleared.

Defaults will affect the game everywhere, but you can activate or deactivate one as mod if/when needed, ( WITH "-" PREFIX = off ), or use JSGME method for switching mod.

About sides: some planes are normal as blue, others normal as red, these are all "summer" as above. Anyother choice ( or countries) may be a "summer (multi)".
About maps: some are summer, some winter, some desert. Defaults do sometimes are a match for these map selections.