you can clamp a paur of spanners together to stop the cams moving, but it really is easy to time them up
as for the crank, just ensure it stays at tdc
the crank pulley bolt is very tight, but the pulley just pulls off
you don't need to replace any of the balancer chain components, only if you want to
when you have refitted the cam chain, double check every timing mark twice, especially the crank
if you turn the engine over the timing marks will all move, don't worry, they will all be 1 link out, or 2 or 3 etc