I thought the old BFII had it set up so that you could play with OT or PT armies on any map (but not a mix), and you got the corresponding set of heroes depending on which era you were playing (i.e. Empire vs. Rebels on Kamino or Republic vs. Separatists on Hoth is fine, bout you couldn’t do Republic vs. Empire or Separatists vs. Rebels). Whether that’s how it used to be or not, that’s how I’d like it to be now.
You are exactly correct. Just checked out Battlefront 2 myself to make sure. Also had some good time destroying x-wings left and right in a space battle above Geonosis.
There are TONS of mods for OG BFII on PC. Custom 7.77GB disc which installs to 35GB or so if all mods are selected. Very worth it.