are there any mods for the IN-game multiplayer so i can have some AI planes fighting, flying, taking-off, and respawning while playing LAN mode with my friends?
Yeah there is. It's called Zuti Moving Dogfight Server. If you are using UP 2.01 or HSFX, they have versions of it that you can use. If you are using the new 4.10 patch from DT, then the MDS is built in and is accessible from Full Mission Builder. Unfortunately, you cannot just throw up a dogfight server and have all maps doing what you have asked. You will have to build each map seperately and place them in your Dogfight folder. I do not know all the ins and outs for setting this up just that tose are the basics. I would recommend reading the manual for 4.10 for more detailed instructions.