If two rules are in conflict, the earlier rule is followed. Oxidation states for all atoms in a pure element are the same.
Oxidation states for all atoms of one type are the same in a binary compound.
Fluorine is always -1. Other halogens are -1 except in their compounds with halogens or oxygen. In binary compounds, the element with greater electronegativity is given a negative oxidation state. The reducing agent gets oxidized - the oxidizing agent gets reduced. You can separate ionic compounds, but they must be restored in the final balanced reaction.