Yes I have two clams and a galaxia and frogspawn(which are considered LPS), it all depends on where you put them in the tank, and if you acclimate your LPS to more light they should be able to handle it just fine
Well to much food would make ammonia but your biological filter should get rid of it right away, I would say with adding all of the stuff your tank is going through a small cycle, the biological filter has to catch up to the larger bioload