Hi

please look at this photo:

Verteilerläufer picture by felicianer - Photobucket

the distributor finger is a little bit burnt (right)... what could be the reasons and could this be a problem?

That looks fairly normal to me, unless I'm missing something. Oil, grease etc can make the burns worse.

Does the car run ok? If you have any doubt, fit a new arm and cap.

Yeah the car runs quite normal... sometimes, when the engine is cold i feel it want to run faster as it can...

It looks pretty normal to me. The thing to worry about is burnt deposits on the bakelite insulated part, not discolouration on the copper track between the centre and edge contacts.

ok nothing to worry about.

what issues can a blocked fuel filter cause?

I used to give it a quick clean with a flat bladed screwdriver if I wasn't changing it. I don't think they are much to replace (the offical name is a rotor arm!)

ok nothing to worry about.

what issues can a blocked fuel filter cause?

Fuel starvation, which can manifest itself as a lack of power and/or a misfire, depending on how bad it is and how you drive.