You have to consider that Russia and Israel are not enemies. Far from that. I am not aware of any Israeli or US airplanes shot down over Syria. One Turkish airplane was shot down, IIRC, but that's their own murky business.
I think Russia does have an interest in Syria; however it doesn't have any interest in Syria that is out of control. Russia also doesn't indicate that it will do anything to actively intervene.
Destruction of chemical weapons facilities is not a bad thing for, actually, everyone except AQ. Assad is afraid to use these weapons, for a good reason. But he has no means to protect them. AQ is ready and very much willing to use chemical weapons against everyone - so they must be denied that. Chemical weapons are not valuable in this conflict; they are just a huge liability. (They are a liability for any country that owns them, actually - that's why they are being gradually destroyed.)
“You have to consider that Russia and Israel are not enemies.”
Believe it or not, a lot of terrorists throughout history have either been trained by the KGB or the FSB. They are indeed close allies to Iran and Syria. One should not get confused with what Russia says and does publicly, or what their short term goals seem to be, as their long term goals seldom change.