Alright, quick question. BotRK on Wukong?

terrible. wukong is not an auto attack based champion. youre better off running arpen items

You don't. Your job is to assassinate the squishies and initiate for your team. You shouldn't be messing with the tanks, that's not your concern.

If I were you I'd just accept that after a certain point you aren't going to be able to kill Mundo solo most likely unless you get fed. But with Wukong that's not your job. Kill him if you can early, but when he gets really tanky you should shift your attention to the enemy team's squishies. Don't build BotRK on Wukong just to kill a tank. It's just not optimal for him when it comes to killing his primary targets which should be the enemy carries.

Never. If you want something to help against tanks, you get . Your job as wukong is to go in, and destroy squishies with your insanely toxic ult.

(Note: I don't consider wukong as a whole toxic, only his ultimate)

No. Never build it. End of story.

I wouldnt recommend it. Unless its like a 4th item investment, but then again its better to have your ADC/APC deal with Mundo. Your job is to kill the carries or peel for your carries by knocking everyone up and trying to hit priorities targets with it. Wukong is big enough threat for Mundo not to peel, but how can Mundo peel Wu? His Q wont stop Wu from using his E-R.

If you have problems killing him in lane then go ignite top or something.