Education on Android devices, and question on USB port usage

[thedicemaster]

how USB host works varies between devices.
many older devices can't use it at all, some have a dedicated fullsize USB host port, but most newer devices have a microUSB port that supports host when you connect a USB-OTG cable.
some high-end devices(like samsung galaxy S and note series) can even use their usb port in host and slave mode at the same time when connected to a smart dock.

so with the exception of a few older devices, there's no need to manually enable host.