Yep, the table is completely general and the combos listed on rob are guidance which you can infer from the table to try a specific one from the giant list.
Take the middle of the range of one of the many ROB combos and compare to his magic number. So for instance d-throw->dash->FJ->f-air->J->f-air true combos between 24 and 34%. Middle of that range means 29%, R.O.B's magic number is 39 so it's a true combo sweetspot at roughly -10 relative to magic. Kirby is magic number 22. I should be able to land d-throw>dash->FJ->f-air->J->f-air true combo on kirby circa 12%. (I haven't even tested this one much since it's new, tell me if it works).
What it doesn't tell you that trying for say the fancy up-tilt -> up-air -> CS vs. pikachu is difficult, and should only be attempted at the edge of the range of the combo. Likewise doing grab->up-air->up-air->up-B on Zero Suit can be very hard because her bounce and hurtbox doesn't connect well with the up-air hitbox. Both *are* technically possible, but you need to apply the right combos for the right characters and a simple, general table as guidance is better than listing every character specific *best*.
You are exactly right on the math for rage. I will make a video when I get time (maybe in a week or two) showing this visually since it's been a constant source of confusion.
Rage shifts you forward in the table, staleness shifts you backwards. So Mario at 35% with 100% damage on Samus means you have to SH-CS instead of CS.
F-tilt staleness is good, but again, it's a few %. The biggest impact is from what portion of the leg you hit with. I would worry less about staleness of f-tilt and more about spacing the move to get the appropriate hitbox, my opinion.
As for pivot dropping the bomb, some characters, for whatever reason, have a hurtbox at their toe level. So if you just push them and drop the bomb, the bomb may prematurely explode on their toe and you'll miss the d-air. Pivoting ever so slightly away avoids this problem. It's not that many characters (I don't have a list, DK for sure).