Yeah, you have easy potential for 5 MPH increase. And relatively cheap. Taking the hook out should help, and definately smoothing the bottom out.
Also, look around the boat, and notice how much useless junk, or "emergency repair items" you have on it. I was always guilty of carrying so much repair crap on my ten year old boat "just in case" I probably had a couple hundred pounds in that alone.
Props - um yeah, chewed alum. vs. Stainless
I'm no expert on any of this by any means, but start asking some of the prop guys what you should try for pitch with the SS. It's not going to flex as much as the Alum. so your gonna need to run a different pitch, and cup... etc.