In response to your first question. Read the first line of my original response. I’ll restate it in a different way in case it wasn’t clear. If I’m loosening the bolts on the transmission pan, I’m removing them all and replacing the gasket. Saving myself a few bucks worth of gasket and fluids is not worth risking having to do it again. Best case scenario I saved $6-$20 by reusing the gasket. Not worth it to me. Do it right once (a second time) and then don’t worry about it.

If you’ve loads of time and want to risk having to be back under the car a 3rd time and having to buy a new gasket and even more fluid, be my guest.

If I’m dropping the pan, I’m replacing the gasket. You’re already doing the work a 2nd time, why risk a third? Gasket shows as being between $6 and $20 depending on where you get it from. Not worth my time to risk fudging it and have to get under the car again and buy more fluid.

That being said, I can’t say for certain that I’d drop the pan just for the magnets. I might stick them to the outside of it, or get a drain plug with a magnetic tip.

In theory, the transmission (or any other component) should be at its best right after it was rebuilt. Unless they only replaced some internal parts or just did a service, this feels wrong to me.

I would recommend taking a close look at what work was performed/charged.