I'm not planning on retexturing/modifying in game models right now; you might wanna look for that skin instead:
Some miltary outfits have a chance to spawn at heli crashes or in military areas.
Another solution would be to look for the class name of a unit you like better, open the pbo mission file, and edit the packageMenu.sqf file inside the cheat folder.
As for the re-arm feature, if your units already have a gun fully loaded when spawned, ...well they don't need ammo do they? ^^
They'll pick up a gun if they run short on ammunitions - and if it's a better one, but I'm not sure about that one.
EDIT : Also guys, don't hesitate to look for retexture replacement packs on armaholic : lots of them retexture desert camo into woodland for most of the BlueFor units, and some are pretty nice ;)