Turkey was cornered and a push against Sirte was not possible. If Algeria had come out more vocally (like Egypt) in support of GNA, Sirte could have been taken. A lost opportunity, unfortunately.
This is a ridiculous hypotheses. Russia will not attempt anything inside Turkey. The temporary deployment of fighters is signalling to Turkey. This could be regarding the extend of the upcoming Turkish operation.
Based on TB2/ANKA surveillance missions, Ayn Al Arab city + country side will definitely be the target of the next ops. Ops could extend to Tel Rifat and Manbij.