There isn't a lot of guess work in how Child Support is handled.
Generally, both parents share extraordinary expenses for children equally.
While each parent may each have the child(ren) roughly the same amount of time, the parent with the higher income may still be required to pay child support. Generally, that's figured as the difference between child support payable by either parent, based on respective incomes, if they had the children full-time.
If you earn about the same and co-parent equally (between 40 and 60 percent), it's a wash.
You can vary arrangements by mutual written agreement, but that requires a co-operative spouse - and for a court to approve it, it still has to test as equitable and usual.