How would federalism and the constitution apply to abortion? do they have a say in a national level or is the choices made by each state?

Not documented: Abortion is not an issue that was even thought about by the Founding Fathers. Legislation and court decisions in these areas are covered under first amendment rights and personal liberty. There are national guidelines (such as Roe v. Wade) but each state can make some limitations based upon their legislative action. My philosophy? "Don't like abortion? Then don't have one."

Those who favor: Federalism, are in favor of a more powerful central government on the national level, whereas those who are "anti-Federalists" prefer a weaker central government with more decisions/power given to each state to decide. Federalist power is limited by the Constitution, so the court's interpretation of the Constitution also plays a role in the power the central govt has. Hope that helps.