Is it possible to drive by car from Jakoruda to Samokov via Granicar? I have such a road on the roadmap of Bulgaria.

No, the section between Treshtenik and Beli Iskar dam is dirt road. As far as I remember there is a check-point on the border of Rila National Park in Nehtenitsa location and driving beyond it is restricted. Still more, the valley of Beli Iskar is reserved for office use only as a part of the dam's system, it is forbidden for citizens.


Is it possible (and allowed) to drive farther than to Rilski Monastir? I mean in the direction Ribni Ezera. If so, how far?

Yes, as far as I know it is allowed to drive to the end of the road in Tiha Rila. There is asphalt only up to Kirilova (or Partizanska) polyana.


Is it allowed to walk the ridge west of Ribni Ezera - from Mramorecki Preslap by Teodosievi Karauli?

Yes. There aren't painted markings after Rilets peak, but the ridge is passable and very impressive. The biggest trouble there is finding practicable path for descent.


Is it allowed to drive by own car to Wihren hut?

Yes.


Are there also buses? Do you know at what time goes he first one? And the last one?

Yes, there are minibuses. Unfortunately I don't know anything about their time-table.