Congrats on your purchase, Vince...

1. What is the best oil to use for the crankcase.

I like Castrol 20W-50 in hot weather and 10W-40 in cold.

2. What is this about oiling the carbs....And what oil should I use...

SU carbs use a variable venturi system. There's a dome with a piston on top of the carb, and a tapered needle attached to the piston meters fuel from the jet. Airflow through the carb raises and lowers the piston and needle.

SUs don't have accelerator pumps. Instead, the rise of the piston is delayed as the throttle opens by damping oil in the dome. This keeps the venturi small, which increases airflow velocity, which draws more fuel from the jet, which richens the mixture until the piston overcomes the damping effect of the oil and rises.

The thicker oil you use, the more richening, and the quicker the throttle response. I recommend 30W motor oil in the domes.

3. What is the gas octane rating I should use...

The lowest that doesn't ping (detonate) with whatever ignition timing gives you good performance. There are too many variables for me to make a blanket recommendation.

4. What type of brake fluid...Dot4 or Dot3

DOT 4 or 5.1. Personally, I use Castrol LMA.

The gearbox and rear end both get 80/90 gear oil, BTW...