Yes, the Galaxy S5 was the only Samsung flagship using the micro USB 3.0 port. They backpedaled to micro USB 2.0 in S6 and S7, and then migrated to USB-C in S8. I'm not sure about the Note series.
The micro USB most of us know already is a USB-B. Each cable before USB-C had USB-A on one side and USB-B on the other. The square-like one used for printers is a full-sized USB-B, as opposed to the one used in phones (micro USB-B).
Unlikely, the A plugs are for the host devices while the B plugs are for peripherals. It got blurred with smartphones (see: USB-OTG) but in general the host devices were big enough to have full-sized USB ports, so the smaller USB-Bs are extremely rare.