VF500F - brake fluid and friction zone

Hello, all. After about a month of fixing her up, my '84 500 is on the road. I am the third owner. Mileage is around 37k. It seems pretty solid, just needed a few parts and a good cleaning. This forum has been lots of help. I have been able to find most answers using search, but I didn't find what I was looking for in regards to synthetic brake fluid.

Is it ok to use DOT 4 synthetic brake fluid in a bike this age? A friend said that I should make sure its ok because synthetic was not around when this bike was designed. He said it might damage seals, etc. This had crossed my mind when I went to buy the brake fluid, but all that was available was synthetic. Also, I read somewhere that all brake fluid is now synthetic. Is this true?

Another question I have deals with the friction zone. My bike doesn't really seem to have one. Its all or nothing. I am having a real hard time starting from a stop. I've never stalled a bike so many times. There doesn't seem to be any slipping or other noticeable issues. Is this a sign that something is wrong or is just the nature of the bike? Most of my experience has been on much newer and smaller cc twins.

Anyway, regardless of a few issues, the bike is a blast to ride.