T500532 is not the correct one for the US market - that would be T2500564*
The key-switch assembly is exactly that - the LOCK
AND the SWITCH, so it does come with a new key.
The overall lock-set includes the Accessories and Panniers Lock Barrels to match the new Key; if you have either of those, you will be using two keys if you just buy item #2 (T2500564*) on fiche, vs #1, complete lock-set.
However it is possible to separate the mechanical key-lock from the electrical switch assembly and swap them - it does require removing the shear-bolts which requires some minor surgery (as being shear-bolts, the heads have snapped off during assembly)
There is a guide on how to dis-assemble the switch in this thread -
http://www.r3owners.net/threads/diy-ignition-switch-repair-get-home-keep-your-locks.22420/