At first glance, I don't think those new K7500 boots are going to be a hit with hardcore rock hoppers. Not enough spikes and I'd question how the sole is attached. On the plus side you can replace the soles ie spikes which is what they are marketing. If you want studded boots as an alternative to Korker sandals, try LLBean Aqua Tread or Hodgeman something or other (these are ceramic studs). Neither have enough spikes, but you can send the LLBean ones back if they wear to fast.
Sandals are you best bet.
Stocking feet are water proof. They are made of neopreme. My experience has been that boots usually feel bigger than their size so I wouldn't go up a size. You best to go try a pair on with your socks included.
Good luck