Vacuum out the hopper on the grinder, and the doser unit so all is clean. Cant see any problem with quarantine as any residue is not from raw bean material.
Clean the coffee machine as per normal, group head brush, blind filter, soft cloth etc etc etc.
There really is no reason to drain the boiler anytime, except when removing an electric element.
There are ways to drain the boiler, but they involve mucking about internally which means the person doing it should be well qualified and know what he/she is doing. But there is no reason to do it just because you are moving.......
Pack it up as per original so that it is supported in the way that the manufacturer originally intended inside the carton, put FRAGILE" tape around the top of the carton, write "THIS SIDE UP" all over it (yeah I know its already printed on the box - like the word fragile - but no one takes any notice), and put it with the rest of the stuff.