Am I asking for too much in 1 camera? D300, D700? for HDR (AEB) & mPixels Can't decide.

This is not accurate. While I don't own all the Nikon bodes, I can tell confirm this:

D7000 offers 3-stop AEB in 1/3 increments up to 2-stops. The 3-stops can be normal/under/over OR can be normal/under/under OR normal/over/over

D600 offers 3-stop AEB in 1/3 increments up to one stop. After that, it is a full stop for up to 2 additional stops. In other words, 1/3, 2//3, one stop, 2nd stop, 3rd stop. As well as the same over/under frames as above.

D300s offers the most. Up to 9-stop AEB in 1/3 stops though out, but only as a "normal" bracket: equal number of negative/positive shots. It can do a 2 or 3 frame bracket going just over or just under.

If memory serves, the D90 offered 1/3 stops and so did the 5100. I can't image the "better" bodies aren't similar to the D300s.