Most chain saws have an automatic oiler the is run by mechanical means or engine vacuum. A few have only a manual oiler that must be pushed. Some have both. Necessary for all is the filling of the...
I most likely corresponds to the chain's drive pitch or gauge or another special characteristic of that specific chain. First figure out who makes the chain, then consult a guide to their markings,...
Chainsaw manufacturers recommend their own brand of chain for their chainsaws. However, you can use any brand as long as it fits or is made for your model.