You do not specifically have to use numpad to enter 1234. The other numbers will work too.
Alternatively you can boot it up with debug serial connected with will do auto-login on first boot.
Maybe it became too common knowledge that the following baud rates are most common:
Amlogic and Allwinner SoCs: 115200
Rockchip SoCs: 1500000
And yes, this could be documented somewhere if it isn't already on docs.armbian.com
Armbian does not mess with ssh settings besides allowing root login. It uses default values that userspace packages ship. Therefore also hostkey generation is straight forward as plain Debian/Ubuntu on x86.