The '62 Topps master set (on the PSA registry) has an additional 14 cards if I'm not mistaken, not seven. The super set, on the other hand, has an additional 92 cards.
The variations aren't rare, although there's obviously competition for them. For the most part, no card seems to be scarcer than it's counterpart.
Here's yesterday's VCP for each of the variation pairs in PSA 7:
22 1st Series Checklist (#33-88 on back) 23
22 1st Series Checklist (#121-176 on back) 19
129 Lee Walls (Plain Jersey-Facing right) 12
129 Lee Walls (Pinstriped Jersey-Facing Left) 32
132 Los Angeles Angels Team (Inset Photos) 49
132 Los Angeles Angels Team (No Inset Photos) 15
134 Billy Hoeft (Blue Sky) 53
134 Billy Hoeft (Green Sky) 59
139 Hal Reniff (Portrait) 81
139 Hal Reniff (Pitching) 44
147 Bill Kunkel (Portrait) 16
147 Bill Kunkel (Pitching) 32
174 Carl Willey (With Cap) 31
174 Carl Willey (No Cap) 15
176 Eddie Yost (Batting) 14
176 Eddie Yost (Portrait) 16
190 Wally Moon (With Cap) 66
190 Wally Moon (No Cap) 26
192 3rd Series Checklist (177-264) (with ,) 18
192 3rd Series Checklist (177-264) 15
441 6th Series Checklist (430-506) (Large Print) 35
441 6th Series Checklist (430-506) (Small Print) 27
458 Bob Buhl (Plain Cap) 39
458 Bob Buhl (M on Cap) 35
462 Willie Tasby ("W" on Cap) 20
462 Willie Tasby (Plain Cap) 17
516 7th Series Checklist (White Boxes) 40
516 7th Series Checklist (Yellow Boxes) 54