I noticed MotoGP racers differ on how many fingers they use to operate the brake lever - some use 1 others 2 or 3.  Is their any advantage one way or another?   I've been using 4 to operate the clutch lever and only 2 to operate the brake lever. Just seems more comfortable that way.

I say whatever is comfortable as well. I'm also a 4 clutch, 2 brake guy.

Four fingers for the clutch,  but only one for the brake, here.  I brake with my middle finger and just lay the index finger on the lever near its pivot.  This leaves the ring and pinkie fingers free to grip the throttle tube to blip on the downshift. 

I get better feel for the brake using only one finger.  More powerful brakes require less manual input to stop....and I have pretty big hands.

Whatever is comfortable for you. I used to use 4 fingers for clutch and 2 fingers for brake, but after I changed the stock clutch and front brake levers with a short levers, it's two fingers on both.