Russia is such a staunch ally with the U.S. against ISIS that it has openly allied with the Assad regime to launch massive bombing campaigns targeting other rebel groups in Syria who were also fighting ISIS and the civilians, hospitals, etc. in cities held by those groups.
Are you talking about guys like this one? "Moderate" rebels.
Nope, that guy has been deceased for some time and to my knowledge never took part in the Syrian civil war. I think President Obama took him out.
This is the kind of atrocity I was referring to that Russia carries out in the name of attacking ISIS, but which targets areas held by other groups also fighting ISIS:
https://www.theguardian.com/global-development/2017/feb/17/msf-inquiry-indicates-russia-was-behind-hospital-bombing-in-syria-medecins-sans-frontieres