Yup, if you have the time then why not put the blood and sweat in the mix, but overall you should not have to do that much adjusting to the EQ throughout the song it should be a set in stone setting once applied to the audio.
Dude.. if you make beats and dont have a keyboard get one.
http://www.sweetwater.com/c513--M-Audio--Keyboard_Controllers
I'd go with the
M-Audio Keystation 88es if you have the space if not a nice 49 key will do just fine.
Take note that he is bouncing around like a fucking rabbit in that video. WAYYY different from standing still and singing. I ain't defending the guy, but it doesn't validate your point that he cant hold a note.