One of the basic keys to success in orchid growing is making sure the roots have airflow around them. They actually do not "need" to dry out between waterings if air flow is maintained. It is when water, trapped between potting media particles, completely blocks air flow, that the roots suffocate and die. I think you might water that first plant more frequently.

English to metric - in rough terms (and for Epsom Salts, that's certainly god enough) 1 teaspoon is 5 ml, and a tablespoon is 15. A teaspoon/gallon, therefore, is 5/3.78 = 1.32 ml/L.

As far as the "keiki monster" is concerned (I'm copyrighting that phrase right now), some plants are genetically predisposed to general basal keikies. Personally, I'd tear that sucker apart to make the "mother" plant manageable, and pot up the babies to share with friends. Yes, you're going to do some root damage, but after separating everything, let them all sit out for a day to dry all of the wounds, then pot them up.