Hey there Paul,
The endpin jack on all Taylors I've had my mits on are the same: the hole is ready to go for a standard endpin jack. Choose your weapon and install, easy peezy.
Lots of opinions on lots of pickups, so that's really up to you and the roll of the dice. But I, in a likely dissenting voice among many, personally dislike the K&K. Its tone is wholly unnatural on its own, and
even through a DI-preamp with tone stack, and
even through a good console, I could not EQ it to a natural acoustic timbre (to my satisfaction, anyway). I tolerated mine for a time, then just eventually ditched it. Look at LR Baggs' and Fishmans' various offerings as there are lots to choose that vary in price and complexity. But for my money, I'd easily stick with any Baggs or Fishman as my top two choices for an aftermarket pickup: solid, reliable, and can be EQ'd to sound like a natural acoustic. IMHO, anywho

Edward