Plain bearings are used for main bearings and connecting rod bearings.
The crankshaft of a typical in line four cylinder engine has 8 balance weights.
Camshaft in an engine is always mounted parallel to the crankshaft.
In a four stroke engine for each crank shaft revolution, the camshaft revolves one half turn.
A camshaft on a four stroke engine runs at 1/2 the crankshaft speed , the intake and exhaust valves opens once (each) for each two engine revolutions. In a two stroke engine, it is one to one.
The timing belt is attached to the camshaft pulley and timing belt drive pulley.