Well, for starters, I'm not sure if you're the SAME John that originated the Post. (The e-mail addresses are a little different BUT you can have multiple addresses.) If I assume you're the SAME John, then I don't know what you're talking about because in your original Post, you said you have OSB for your sub-floor. OSB is NOT waferboard. THEN, on the other hand, if you're a DIFFERENT John, read on ...
1) Waferboard will 'chip' when nailed. The nails won't hold nor will screws UNLESS you screw down into the joists or sub-floor below (if there is one.) You see, by 'walking' on your floor (which is what you're suppose to do, ha-ha), the compression and decompression of the floor will 'work' nails and possible screws 'loose' in relatively short-order. The ONLY way this wouldn't be a problem is if you nailed/screwed into the joists (or sub-floor below assuming there is one. I already mentioned this.) I don't really recommend that you have waferboard down, even if there's a plywood sub-floor or not. (You'll most likely VOID the Warranty, but to be SURE, you can check w/the Mfgr. about your particular 'installation setup' ...)
2) You could go either way. The DOWNSIDE to going over top of what your have with a 3/4" plywood or something is that your doors and 'room-transition' points may need some 'work'. Doors may need to be cut, and/or you may 'trip' going from, say ..., the kitchen to the dining room (assuming you're flooring is being put in the dining room, among others.) There are transition strips for the latter but you may not like the 'end result'. Obviously, if you RIP up the existing waferboard, and re-lay an underlayment that's the SAME thickness (hopefully 3/4"), then you won't have to cut any front/kitchen/back doors or closet doors, nor will you have any 'difference' in how the floor transitions from one room to the other. Bottom line, the plywood / subfloor underlayment 'should' be screwed to the joists, then the hardwood goes on top of that. (The SAME 'rule' applies if you just cover the waferboard. You need to screw THROUGH the waferboard, and into the joists. This way, the floor doesn't 'move' or come loose on you over time. Again, check w/the mfgr. about your 'installation setup' to see if they 'approve' ...)
3) If you lay ANYTHING on top of ANYTHING, do so at 90 degrees. This is one variable in creating a 'sound floor'. In other words, if your joists run North (N) to South (S), then the sub-floor (other than on a 45 degree angle), normally runs E to W. Then, on top of that, the hardwood runs N to S. HOWEVER, if you want your floor (in this example) to run E to W, it's best to lay a 1/4" plywood underlayment in a N to S direction FIRST, THEN lay the hardwood on top of that in an E to W direction. The idea is to have EACH layer, underlayment and hardwood et al., running OPPOSITE directions to each other (in a perfect world.) The idea behind running layers at 90 degree angles is for stability. (W/O stability, you'll get squeaks and weak spots.) Do you see why the layers are best installed at 90 degree angles??! There are exceptions but w/o knowing exactly what you have, I'll hold off. Feel free to tell 'us' what you have on the floor, starting with the joists (and at what angle they 'layers' run w/each other.) I hope I'm not confusing you. I apologize in advance if I do so.
To make things a bit more complicated, even when installing a layer 90 degrees to the one below (hardwood flooring 'layer' being the exception), you need to cut your sheets so a seam DOESN'T 'line up' with another seam in the layer you're installing over. This is critical so make sure your seams ONLY 'cross' at 90 degress to each other; NOT parallel (or in line with) each other.
Perhaps someone else can say 'the same thing' in other words so you can understand what's being said. Again, I apologize if I'm confusing you. My best to ya and hope this helps.