I think that for each situation there could be many explanations, and one would have to assess the probability of all of them happening and then decide based upon such an assessment - finally choose the most probable and easily achievable.
>>first situation
> I wonder if it's possible that you saw multiple satellites at once moving in the sky?
I have a sketch of what I saw from that period, but it does not have enough details to investigate it now. I would not like to discuss based on false personal memory after such a long time.
Still, I could add (out of my memory of what I saw) is that the lights (stars) were in a long rectangular (or cylindrical) formation, were brighter than the rest of the lights in the night sky (brighter than the rest of the stars). They all moved together in sync (imagine looking at a train painted nonreflective black with randomly dispersed luminiscent dots all over it, they will all move in the same direction and with same speed). I was in central Europe and was looking towards south-west, the objects were moving from the south-west part of the sky towards the south part of the sky.
I don't think that there is big enough probability of having that many satellites in a rather narrow patch of the sky (they can't be on the same orbit, so they would have to be on 100 different orbits and still look to be in the same place and appear as to being part of a big formation).
I think that some optical phenomena would be a better explanation of what I saw. Maybe we were looking at a projection of many starts - but projected from where and how.
Most simple and believable explanation is many airplanes flying in a formation.
>>second situation
>I wonder if a meteor could bounce when it hits a denser part of the atmosphere and change direction a bit, and maybe it was only the angle you were seeing it from that made the change in direction look as extreme as 90 degrees?
Optics (refraction, reflection and parallax effects) can explain such a thing if there was some barrier which was met by the object or was introduced on the line of sight between me and the object.
If if was a meteor (which most of the time you don't see until it hits the atmosphere and starts burning) then it would lightup even more upon hitting something. Plus meteors usually have a trail, which i did not see.
The speed must have been immense, since it crossed the sky in a mere instant. I would expect an even bigger flame and trail with such speed.
I can't recall if it was completely dark at that moment or shortly after sunset, but it was in the evening and I was looking to north - northwest, and the object appeared from the west part of the sky, and exit on the north part of the sky, after changing direction (so it was moving from west to north in the begining and then changed north). This are all aprox directions, just to have it illustrated.