He may not need a new plug. Mine came with an NGK already installed.
The bikes from factory are equipped with the Bosch WD7DDC4 spark plug. Some dealers may swap it for the NGK during initial prep of the bike. But most don't.
Regarding the tools - I have mostly relied on the existing tool-kit that comes with the bike for minor stuff. It fits in the LH toolbox (where the fuses are located) and should always be kept there. However, if you are servicing the bike yourself, you'll need a whole set of spanners, wrenches, sockets and the like - which I'm sure you'll have. For chain adjustment, you will need to get a 30mm hex socket for the main axle nut. And a 19mm socket for the brake anchor nut. Similarly, for oil changes, you will need appropriate sockets for the M6 bolts. Clutch free-play adjustment can be done easily with standard set of spanners.
After riding the bike home, go over as many nuts and bolts you can see on the bike. Check for tightness. Do not loosen any. The header pipe bolts may seem loose, but tighten them to an extent where the flange is flush. Tighten those bolts evenly, if they are loose. Other than that, follow the break-in speeds according to the manual. And do not forget the initial 300mi oil change. That is crucial and should be done at that mark. Do not delay that one. Also check your battery connections - check if they are snug and are not being over-stressed due to excessive bending in the cables. Similarly, check all electrical connections and connectors to see if they are tightly fit with each other in the clips.
Keep the tyre pressure to what it shows in the manual. If you have any other questions, you can always rely on this forum.
Ride safely and enjoy.