You have made the same mistake graphically that I made physically at first. Sorry for not being clear enough.
In that picture, you have actually encircled R353/R352. These are _not_ identical to R135/R136. R135/R136 sit directly below the encircled resistors in that picture. R353/R352 can stay, R135/R136 have to go.
A correctly modified board looks like this (test if I can include images from the sunxi wiki):
I have now corrected the wiki page. I could not replace the image with the wrong resistors highlighted, so I uploaded a new one with a different name and used this in the article to highlight the R135/R136 resistor positions:
Fuses are a good idea, but we're talking about 24V here. Enough to make a spark if you've got a big enough source (e.g. car battery) but in low currents it should be entirely safe to use.
650mA * 24V is 15.5W, which is the same limit as normal 802.3af. If they are not a one-time fuse, I would guess they're a polyfuse, meaning they are heat activated. The same kind of fuses are used to protect USB ports from over current.
However looking at the photos on Amazon, I can't see these fuses anywhere. If you buy this injector I would verify that there are actually fuses installed.
200mA * 24V is only 5W. In my opinion this is cutting it too close, you're very likely to have the fuse burned out at some point due to a current spike (e.g. if you have a power failure and all Orange Pi Zero's restart at the same time). I also think that 3W for 4 Orange Pi units with Ethernet and WiFi is too conservative.
I would recommend using a larger fuse. Something around 1A (24W) will provide both enough head room for all Orange Pi Zero units to run and yet still provide the protection you're seeking.
24W won't generate enough heat to cause a fire, even if there's a direct short.