OSCE observers don't wear military uniforms and, especially, unit insignias. By international law.
They are probably battle tourists or mercenaries from whatever "Blackwater" is called nowadays.
How many roubles is one US dollar?
1$ is around 50-60 roubles, it is fluctuating right now
(From another thread)
Has the rouble exchange rate stabilized? And is Russia/the Russian Central Bank still spending enormous amounts of money on maintaining a non-crazy rate of exchange?
It's still fluctuating, but not greatly, in the region of 63-66 roubles per dollar. Central bank is still spending money, which we still have piles of, but less than it used to.
Some slightly more objective reporting on events at Mariupol. One rebel commander says "yes, we are responsible for the shelling of a civilian area", one says "no, it was the Ukrainians". Make of it what you will. The rebels seem to be gaining ground, but at great loss of men and materiel. No info offered on Ukrainian losses, though I expect them to be signifigant, considering the nature of the combat.
Rebel commanders tend to squabble between themselves and play blame games, so I'd not expect their opinions to be the objective truth, either. Ukrainian losses are almost certainly higher than rebel losses, considering that the rebels have so far been winning most battles despite being significantly fewer in number than the AFU.