@rspooner For injury prevention, I'd make sure to do some sort of face pulls or band pull aparts or whatever the bwf equivalent of those is and also to do a lot of pull ups.
For core stability, I would do three different isometric holds. One in the pushup down position, one in the up position and the third could just be a standard plank. Then you do some progression with equal rest between the holds all the way up to maybe 3 or 4 minutes each. Regular planks actually progress fairly rapidly, so if you do this every other day it shouldn't really be a problem. This is probably overkill, and pushup training would likely be sufficient, but I think this would be faster, easier and potentially more optimal.
Then for pushups I would do both a regular volume progression for standard pushups, and then also the sub-max push ups at 50 bpm. If we want to treat this as a proper endurance sport (ie maybe shoot for a higher goal than 100 total), you could do a few days of volume work and then once a week go for a longer set. This weekly long set can be increased by a few pushups a week, trying to peek at whatever your goal total is.