a) Check with OOredoo when you get here. They are the internet service providers here.
b) There are several and choice depends on you. Mozaic and Pehla are two of them.
c) OOredoo is the best.
d) You should be open one in a single day once you get your RP and your Qatar ID.
e) Just take a pocketful of money and walk into the showroom of the car of your choice once you have your Qatar ID and driving licence.