It sounds like fuel starved. Try the fuel filter or the fuel pump.
Could be in need of a tune up Could have moisture inside the distributor cap Could be in need of a carburetor rebuild
The chain can not backfire. If it is installed off time it can cause a backfire, which could conceivably damage a starter.
There could be condensation in the distributor or possibly a worn camshaft. It is also possible that the carberatuer needs to be cleaned or rebuilt.
Yes, that is one of many possibilities.
could be a bad plug
Yes it would.
engine backfire during cranking.
could be a bad battery wire
timing is off or firing order is off
Out of time, or spark plug wires installed on wrong plug.