I don't think the game works like that, buddy. You beat it on normal to get the infinite rocket launcher, on pro to get the PRL, and you beat Separate Ways to get the Typewriter.
Just out of curiosity, what sucks about playing as Ada? She plays just like Leon except she has access to more areas with that grapple gun.
I wasn't necessarily "excited" to play Separate Ways either. But it was cool to see what Ada was doing while Leon was out playing Hero and exactly how she kept saving his ass. Don't worry though it only takes a few hours to beat then you'll be able to get your Typewriter.... as soon as you come up with 1,000,000 pesos.