Hmm, that's an old bike, so, not too sure i will be right, but, i think that the crank case may have a breather pipe that connects to the air filter, it is possible that this may be blocked, or, there is simply too much back pressure from the crank case forcing excess oil out, hope that helps
Must be air in the system, or, getting into the system.
Can be that the pads are well worn initially, is there fluid in the cylinder??
The hoses may be bulging, maybe need replacing
Sorry for the late reply, but thanks for the welcome, regarding the flag, nope, not under Estonia, besides, it's a Scottish flag, all the other UK ones are there