The Justin guitar and Marty ones mentioned previously are probably the best for beginners.
As for the guitar...
Make sure the strings are a light gauge, if they aren't get it restrung, it's not expensive and it will make it much easier to play.
Beginners normally struggle with barre chords and most decent tunes have a fair few in them. To keep him interested, whilst he builds up technique, having a capo which changes the key by clamping across the strings can help, if you transpose the song up one or two steps you can often remove tricky barre chords. There are a number of free apps that will do this for you if you have the guitar tabs.
Don't think of it as a cheat, many professional performers use them when playing live and some tunes actually specify that a capo is required.
Practice little and often rather than hour long sessions a couple of times a week. It's easier on the fingers (which can get sore) and you tend to improve more quickly.