The British Armed Forces accept citizens of all Commonwealth nations (whether a Dominion, or just in the Commonwealth of Nations), as well as citizens of nations who may no longer be in the...
The answer would depend on when and where.
Prior to the Boer War (2nd South African War), soldiering in the colonies was something of an amateur activity and locally raised regiments engaged in...
Various methods depending on the 'crime'. Less serious ones have things like privileges taken away or confined to barracks more serious crimes can earn you time in the military prison or 'glass...