1. The current version is dp2, dp3 is what is in DEVELOPMENT.
2. 3. 4. 5. This is all down to what resource is running on the server, its upto the server owner what things he wants ingame and where.
Resources can be found at https://community.multitheftauto.com or you could make your own, the scripting language is lua
6. A new map editor is in the works, however if you do need to make a map, use the race map editor for the time being and convert the map to dm format (converter on this forum).
7. If by making your own team, you mean clan or gang, then yes.
8. Its unlikely MTA will support other gtasa versions other than 1.0, thats why a downgrader was created. (that can also be found on this forum)