For the mafia thing i know that mafias are for RP and you cant have "territories" or start gang wars. Its strictly forbidden and recently some gangs/mafias were warned for it. For the taxi thing yes, its /setfee [amount] and i think around every 20 seconds it makes them pay the amount. ( amount can be from 1-50 dollars but the higher you set it the less customers will come) And lastly for houses yes, they can enter your house with /enter and if you dont want someone to enter do /houselock and /houseunlock (im pretty sure) You could always do /commands and look on the main page and all the commands should be there.
Good luck, SAPD Captain Vincent_Vice