Stu, Mucha Man’s suggestion about the fold-out plus a more detailed map is good. The Sunriver ones, though great, are a bit unwieldy. I think a one-volume road map at 1:90,000 is better. There are a number of these available: basically the same map in different binding.
A standard motorbike/scooter license (it’s called “heavy” but that just means heavier than a 50) will cover you up to 250cc.
Even 250s aren’t cheap. New 250 scooters start at around 110,000NT; new 250 motorbikes at around 180,000.
I suggest you browse and search around the “Vroom, vroom” forum and gather some information. A lot of information has been posted on these topics before.