Sounds like you have a good start.
You're going to want to consider a second volume knob, possibly from a line driver, or rca line knob, you can control volume with the pad itself but thats kind of a pain in the ***, swiping the screen for volume.
Take a shot of your dash.
If you have room for a 1/2 din EQ that would be the way to go.
Matter of fact, where all your switches are right now is probably the best location, those switches can be easily put anywhere but the eq necessarily cant be.