By new maps, you mean you make them from scratch or you wanna tweak some POE maps.
I asumed you where talking about ServerSide.
When I get my modding computer in order I can help you a bit better, missing a table to put it on now.
ClientSide: Download needed.
If it's your own map you can do what ever with it.
You can even have napalm fire coming out of soldiers behind when they run.
As you probebly saw on my maps you downloaded, I played with whatever on them.
ServerSide: No download needed.
If it's a POE map you can't change graphic or effects.
No possible way to change A-10's bombs graphicly or effectwise. Damage and force you can change.
Every version of BF1942/BFV including mods are basicly the same. Most code works on both versions. You will find codes for the most amazing things on this site. Use them wisely.