As far as the spacers are concerned, you shouldn't worry too much.  Some of the spacers that we had were also pretty tight against the walls.  If you take a pair of pliers and wiggle back and forth you will eventually be able to get the spacers out.  Just be careful to not damage the wall or the flooring too much.  Take your time and it will work out.

The dip in the kitchen should have been fixed before you started laying the flooring.  There are many different techniques for leveling subfloors before installing hardwood/laminate but I won't discuss those in this message.  Putting 2 layers of the underlayment could cause the boards to "cave in" (if you will) while walking on the floor.  You could always try it and see, you can always take the boards back out and remedy the problem after you try it.  That is the benefit of this type of flooring.  Good luck.