"and then dig in and take the years of preparation,rehearsal, backing track editing, or pay someone to create the song tracks & arrangements in the right keys, etc,"

Donny, I disagree. from what I've seem lateley Nigel has the answer. Get the tracks, an all in one Kareoke machine, and lots of them have transpsoe adjustments so he can find where he feels comfortable, and go for it. If he can be personable on stage and sing decent he's there.
Very few acts are putting in years of preparation anymore. Everyone who can sing or thinks they can sing is out there.