only running engine on centre stand,

[Dave48]

The concern is it not that its nothing to do with anything other that the 1st 5 seconds of starting, is the concern that the pump will not have access to enough oil on start up, which side is the pump.

And while I think about it why is the stand on the left on all bikes

Surely the stand is on the left so the bike leans towards the kerb-at least in countries where they drive on the left-so probably historic as far as UK goes?