ordering non stock?

When a dealer does not have a model I want and has to order/locate it, is he
getting it from the distributor or another dealer?

Could be either. Depends on where he finds one, and if he can find
another dealer who is willing to part with it. Don't expect that for
popular models.

If he gets it from another dealer, does he pay that other dealer directly or

Since most vehicles are "floor-planned" they probably just change
records at the distributor for who now has the bike, and owes the money
when it is sold.

how does it work?

Is it more likely for the dealer to give me a discount on models on the
floor, or on models that he has to order?

Probably not, unless it is a model he's having trouble selling. In fact,
you may have to pay more if he gets it from another dealer. There's a
second shipping charge.

My BMW dealer sometimes arranges *swaps* of two bikes with other dealers
(one each way), and he may be willing to eat the shipping costs to make
a sale for a good customer. Don't count on it, though.