If you choose to run higher octane....just more money for the same bang. Some may be conviced of better performance, usually because they have to justify the extra expense!!!
Yes, although some premium fuels have more cleaning additives than regular. If your bike was carboned up a lot (say from riding too gently) then you might see some benefits as the additives clean things out.
Top Tier fuels have a fine additive package for regular. Top Tier Gasoline
If premium is ethanol free and regular has ethanol, I'd use premium over a winter snow season. There would be a mileage boost too as up to 10% of the fuel would have only 66% of the energy of gasoline/petrol. That would help range but the extra cost would probably negate the economy factor.