I wrote an advice about this a while back,
To answer your questions,
The MAF is essential. It measures how much air is flowing into the engine and tells the ECU how much fuel to inject into the cylinder. It is non adjustable, it is just a measuring advice.
The ECU will need to be reprogrammed, probably changed.
On an old worn engine, a turbo puts extra strain. Unless you want to upgrade the internals, you will need to run a low pressure turbo, 10 PSI or less.
You will need new inlet and outlet manifolds, custom made if a kit isn't available. You might be able to keep the rear part of your exhaust the the front will have to be changed.
Anything from 20-200 horsepower depending on how much you want to spend.
A lot.
You will need wasta to get it passed by RTA.