Keys are easy, remove the backs from the doors (note which screw came from which hole). Once the backs are off you can remove the locks. Take the locks to any decent locksmith and he can make keys.
Are they good - no, not really. They were made before the invention of power tools and will pose a low level of resistance to an attack with such tools. However they are going to be better than a lot of the low grade modern junk on the market ….. If you plan to use them as safes don’t exceed around GBP 1,000 in contents and your insurance co should be happy (contact them for confirmation).
I would not remove the paint and polish back to the bare metal as the metal will rust very rapidly if you do so, clean back by all means but then re-paint. Take great care around the edges of the doors etc as if the paint you use is too thick you will not be able to open or close the doors ! Bear in mind when stripping that the original paint is very likely to contain high levels of lead.
As to age - they both date pre 1890. If you find the serial number on the Milners that can be dated more accurately (look on the top edge of the door).
