Not worth the hassle imo. Loads of "disadvantages" and extra work so to speak.
The SPIs/MPIs need a pump because they need the pressure to actually squirt fuel into the engine, where as carbs only rely on there being fuel in the carb bowl, the velocity of air flow running through the carb does all the work by sucking that fuel up through the jet.
If however you're running/converting to a carbed turbo/supercharger set up then yes you need an electric pump, along with a regulator etc and a return line to the tank. As your tank only has an outlet you would need to fit a tank from a FI mini, or modify it and weld on a return fitting., but theres no need, too much hassle for no gains.
The mechanical fuel pumps do a good job, even on a mildly tuned 998/1275 etc and so on. Fitting a fuel filter if it doesn't already have one wont go amiss though 
You're probably overthinking using a fuel cut (electric solenoid along the fuel line) as a method for added security, even thats more work than needs be. Good bet would be to just wire in a switch between the ignition and coil and hide it in a inconspicuous place, or disguise it as something else 
10 minute job and dirt cheap! thats what matters! At the same time though the wiring diagram for a mini is so basic its not hard to bypass most extra security measures, it just prevents the lazy opportunist jumping in and driving off.
You could have all the security measures in the word, but at the end of the day, if they want your mini bad enough, not much you can do 
The best security measure is to highlight all the rust and problems with the car 
or just take out the rotor arm from the dizzy....that left my mate baffled for a while 
Plenty mechanical deterrents. A decent steering wheel lock is a nice big visual clue that lazy thiefs cant be bothered with!
