Practically you're right. There can only be so much information within a finite space (the space here being the wavelengths 390 to 750 nm). But theoretically patrickc is correct as there are infinite amount of variations within a finite space, an example being that there are infinite amount of numbers between 0-1, which theoretically means that each time you count from 0 to 1 you have counted infinity. this also applies to the color spectrum. But practice always comes over theory, and you are therefore the one that has the best answer.

Probably not. But both can be right with good arguments, anon being the only one with good arguments though.