According to the manual, the teller to your left in the bank is called Porto. It is implied that the one on the right is named Bello, but there is no way to confirm this
Koopa's coin bonus increases by ten if you're the tenth to pass by him, giving you 20 coins total. If you're 20th to pass, you get 30 coins, and if you're 30th, you get 40. through concerted cooperation and/or good luck, you'll find that being 40th will give you 50 coins.
unfortunatename of the weird robots in Luigi's Engine Room are Pisudon.