So I have created a monk NPC character, equivalent of a level 11 player. I cried it the way I create most key NPCs, created the character using player rules to figure out the class skills and abilities, then boosted the hit points and tweaked and simplified slightly. 

But, should I bother with Ki point management, or simply have a list of potential bonus actions and not bother managing ki points? 

That depends, how long is it supposed to last and how many fights? And did you give it Legendary Actions?

Quote from Scarloc_Stormcall >>

So I have created a monk NPC character, equivalent of a level 11 player. I cried it the way I create most key NPCs, created the character using player rules to figure out the class skills and abilities, then boosted the hit points and tweaked and simplified slightly. 

But, should I bother with Ki point management, or simply have a list of potential bonus actions and not bother managing ki points? 

 Depends what you're using it for? Tracking chi points are a hassle though giving him infinite stunning strikes would justifiably annoy the PCs. Maybe give him a fixed 2-3 chi points per round or put chi abilities on a recharge roll.

Make Flurry of Blows, Step of the Wind and Patient defense part of the multi attack (e.g X can make two attacks and choose between...) and use a recharge 5-6 mechanic on the stunning strike.

Don't track Ki points, it will make you mad.

You won't seriously mess up the power level by giving the monk one stunning attack per round, and choice of Flurry of Blows, Patient Defense, and Step of the Wind every round. Sure, a regular monk would run out of ki in five rounds doing that, but a regular monk can also use stunning attack multiple times per round.