Here's what I know:
NTSC is 525 lines per frame, 262.5 lines per field. The last line of the first field ends at the bottom center of the screen, and the first line of the second field starts at the top center. That odd line pushes the second field between the lines of the first field. The frame rate is 60Hz for black & white NTSC and 60/1.001Hz for color NTSC.
The SNES and other consoles (usually) don't output the odd line, creating a slightly faster progressive display. The field rate becomes the frame rate. There are 8 lines of VBlank at the top, followed by the active display, followed by 7 lines of VBlank. The first line of the active display is forced to black because the sprite buffers are initialized during that line.
For the TV, line 0 is just a regular line. Many (but not all) games don't account for that blanked line, often creating a line at the bottom that is essentially garbage, easily visible on emulators.
The duration of a SNES scanline is 1364 master clock cycles (master clock frequency is 5 * 7 * 9 / 88 * 6 MHz)
except for certain cases.
