He's already got the first set of speakers?
The second set look ok, but you might want to try mounting your GTO628s to get a feel on how much room you have within the front door cards, they're not exactly spacious. You will need speaker adaptors to pad out the speakers so they dont foul the window mechanism. Fortunately, there are reports BMW Mini
16.5cm (they do 13cm ones too, which wont fit) speaker adaptors will fit (
ebay link).
Tools required = screwdrivers, something plastic like an old credit card incase you need help prising them off.
As Andys1981 pointed out, you'll need to run speaker cabling through the door to connect the crossover box with the woofers and tweeters - doesnt look like the wires are included (halfords is probably your best bet for that)