Shouldn’t be a problem. My daughter travels on 2 passports, Thai and German, always uses her Thai passport to exit and re-enter Thailand and her German passport within Europe. The airlines want to see a passport that will be accepted in the country she is travelling to, sometimes you have to show both passports to the airline, no issue.
No, the bike can only be insured by its owner. A driver who borrows or rents a bike or a car can take accident insurance for himself, although policies sometimes exclude road accidents, but the third party liability and the liability for the bike itself has to sit with the bike owner.
You could look at it the other way round: Thais are getting a discount that foreigners are not, in the same way that sometimes students or elderly are getting discounts that others don’t.
Yes, but depending on your residency, the rules are not the same. Wise has to comply with different banking rules in each country where it has customers. The maximum amount you can hold, for example, depends on the country you are registered in.