Too much oil and you get too much crankcase pressure and you can blow a seal or gasket. You can also get cavitation and other unpleasant things happening inside. If nothing else the increased internal pumping losses will increase fuel consumption.

1 or 2 mm over max is probably OK, but 1 cm is too much I reckon.

I always check my oil levels when cold, when its all drained down from hot, then there is no need to wipe the dipstick either, because its drained off that as well.

Check tyres cold, and then hot, and if the hot pressure is more than 4 psi, or 10% more than cold, you need more cold pressure. Altitude makes a difference too, and ambient temps.