Kerensky had an enormous bias against the Bolsheviks. His compatriots would have sympathized with German invaders (or probably any nationalist faction attempting to remove the Communist government, be it domestic or foreign.) That being said, Kerensky certainly didn't represent the majority. Most Russians, regardless of their feelings toward the government, would have been hostile to a foreign invasion and the indignities, injuries and deprivationsthat come with it. When your country is attacked, a sort of patriotism kicks in. The instinct is to defend and protect, especially if you conflate your lifestyle with your nationality (For a modern example, Bush's approval rating sky rocketed after the 9/11 terror attacks.)

There was some collaboration once Germany actually invaded, perhaps most notably in Ukraine where many residents had long been particularly discontent with the government and ddawn to fascism. In the end, they were punished harshly, perhaps as an example.

Could the Germans expect significant help from the Russian population? Nothing is impossible, but many things are unlikely. The Germans believed that the Irish would support them in their war against Britain. The Nazi higher-ups, including Hitler, may well have believed there would be a mass uprising in Russia - I've never seen any evidence of this, but supposing it's true - It actually says little about the Russians. Hitler and the Nazis had a pathological hatred of communists to accompany delusions of grandeur and a superiority complex. They viewed the world through that lense.