1.) Piracy is not supported so i suggest you buy the game from best buy. Once you have it installed add in the NO CD Crack so you can mod the game and play online.
Download that here: http://www.thegtaplace.com/downloads...sa-no-cd-patch
Put the .exe file in your San Andreas Directory and replace the .exe already there.
2.) In order to create your own fire station and buildings, you need to understand scripting for SA:MP aswell as mapping. To map i would recommend the MTA Map Editor which comes with the MTA:SA Client.
3.) You need to learn how to script to make your own game modes and player spawns. I suggest reading up the tutorials on the SA:MP website and forum.
All can be found here: http://www.sa-mp.com/
4.) same as above