Questions about decoupler force

[iamthemoose]

My apologies for reposting this. I was unable to find my old thread after posting it, and got no views or responses after several hours.

I've got a couple of questions concerning decouplers. To give some context, what I'm attempting to do is launch a satellite into orbit and decouple with the right velocity and apoapsis so that the additional force from the decoupler carries the satellite into a circular orbit (hopefully leaving the debris behind to fall back into atmo).

My questions are as follows:

1. Is the decoupler force applied to both sides, or split between the two? ex. If I put a 100kN decoupler onto a rocket and separate, does each side receive a 100kN force, or a 50kN force?

2. Disregarding mass, is there any reason to avoid using a decoupler of the wrong size? Would a larger decoupler connected to a small section/satellite/whatever apply a smaller force (when compared to a smaller decoupler of equal force), since there would be empty space? Or are there no differences other than aesthetics and mass?

I appreciate your feedback. Have an awesome day!