To start the server, you will need to change the directory to the location where you have the Minecraft Server folder and the.jar file located in it. You can.
You can either pay for a server with realms or an online service (I would search around for a bit to see which host best suits your needs), or you can all sign.
Use /setworldspawn to set the precise co-ordinate of where you want the world spawn point to be. Then set /gamerule spawnRadius 0 to force players to spawn at.
The most profitable ideas are to run your own server or develop plugins for other servers, but becoming a content creator or builder are still viable ways to.
There is three ways: 1) add your name to the ops.txt file 2) in the black or white box (the server thing) do: op playername and once your an op you can op.