I know how a delta potential is described mathematically but how can a delta potential be a 'well'? Does it have particles outside the 'well' and 'bind' it or does it somehow have particle inside it? Also, if we consider three dimensions then won't the potential be present at only one point in ...

Could two photons with same frequency have different amplitudes and so different peak velocities of oscillations perpendicular to their direction? (to make a larger distance in same interval you need to be quicker).