Welcome to KZR, I am partial to the KZ750 4s and have been around them since 1980. Still ride me E1 that I bought brand new.
Brake issue is probably the Master cylinder if bleeding doesn't help. Not uncommon as most folks never change the fluid. Outside chance the caliper piston is stuck but since you said the pedal goes to the stop with no resistance I doubt it.
Your oil leak may be where the tachometer goes into the front of the head. I have had mine leak before, oil ends up running down the front of the engine. There is an O-ring on the adaptor that goes into the head.
There is a pressurized oil passage between the head and cylinder jugs with an O-ring which I currently have seeping oil on mine but it will be on the side and not the front.
Good luck!!
So the old Rocker gets out his bike to make a ton before he takes his leave. Up on the A1 by Scotch Corner
just like it used to be. And as he flies --- tears in his eyes ---
his wind-whipped words echo the final take and he hits the trunk road doing around 120 with no room left to brake.
