I wonder if the distance of a pedestrian crossing from the centre of the roundabout relates to pedestrian safety. Subjectively, I feel like safety could be improved by moving the crossings farther from the centre.
Maybe I'm misinterpreting, but it's frustrating as a pedestrian if you ever are walking along a road and have to take a walk of even only a few metres in a perpendicular direction to find a crossing, cross, and then walk back to the original road.
It could be just five or ten meters in each direction. For example this crossing always felt unsafe to me. The original crossing has been obstructed to prevent crossings and moved about 5 meters out, and it feels much safer now: https://goo.gl/maps/ipe8RXkdSgpZz72r6
I wonder about this specific setup for cyclist. The yield sings when coming in are after the cross walk so here in Finland in those cases the cyclist would need to yield. And even more weirdly as car is turning when going out they would need to yield on that side to cyclists. Is that same or different in Czech.
In Czech all traffic must yield when entering a roundabout, including the tram. As far as I can tell the yield signs are there for foreigners might be used to different rules.
Regarding your second point, if you mean a car changing lanes from an inner lane to an outer lane, it does need to yield to everyone in that outer lane. This includes yielding to cyclists whose trajectory would intersect with the car. Again, the same applies to all traffic.