Neither face’s first ability can reduce colored mana requirements of spells you cast.

For Will’s first loyalty ability, any effects that modify a creature’s power and/or toughness without setting them to a specific value (i.e. ones that don’t affect base power and/or toughness) will apply after its base power and toughness are set, regardless of the order those effects were created. The same is true for counters that modify its power and toughness.

For Rowan’s emblem, you can pay only once. You can’t pay more to copy the spell more than once.

To determine the total cost of a spell, start with the mana cost or alternative cost you’re paying, add any cost increases, then apply any cost reductions (such as that of Rowan or Will’s first ability). The mana value of the spell is determined only by its mana cost, no matter what the total cost to cast the spell was.