[old_tv_nut]

"Instead, I need 5.5 million of DIFFERENT FREQUENCIES, each frequency representing a pixel on the screen."

Stop right there! Each spot on the screen does not have its own frequency.
You need to understand Fourier transforms, which calculate the frequencies produced by a sequence of dark and light spots.

So, a particular frequency (5.5 MHz in your example) produces a continuous sequence of alternating dark and light spots. A frequency of 2.75 MHz would produce a continuous sequence of two light spots followed by two dark spots, and so on. (In analog, since there are not discrete pixels, this would just be a coarser pattern of wider light and dark areas.)

So, each frequency in the signal affects ALL the spots on the screen, but in patterns of different coarseness and strength (contrast). The overall spectrum of a signal represents how much of each frequency is present such that when all these corresponding time patterns are combined, they form the sequence of light, dark and gray spots to make a scanned picture.

If you can first understand this, then we can discuss your further questions, and maybe see why some of them make sense and some don't.