It doesn't make a difference who makes more money. You both can agree on a custody schedule of 50/50 or whatever in your separation agreement. It doesn't have to come to a trial unless both parties don't agree. But you can do mediation and stuff before. A judge only makes a decision if the 2 parties can't reach a mutual agreement. Definitely start by getting a lawyer. They will help you better understand your rights.
It doesn’t matter who makes more money. If you’re married and split he would have to give you spousal support for a period of timeand child support. As long as you’re a fit parent I think the courts are more inclined to award custody to mom.