Quick question when playing Murne Rin and her false orders. If she performs an attack using a hostile figure and that hostile figure is focused - does she get to apply that figure's focus with that attack since it is technically that figure performing the attack?

Yes - Focus is mandatory, it must be used as soon as it's legal to do so

Yes, focused is both the ability of the figure with who the attack is performed with and mandatory and discarded after the attack.