no

simply not possible

kinda, in sofa's vanilla+ there is a kestrel team, basically using less advanced weapons and vehicles than the vanilla+ eagle and raven (there are also magpie insurgents and a bunch of other spinoffs)

wdym? like multiple teams fighting each other in a match? that would be a pretty cool idea.

The only real way I could see that being possible is if a multiskin had various skins assigned to one team. So you'd have one team with, say, blue and purple soldiers (but they'd still be classified as a single team).