#1
He said on his old website that by learning the following songs you would know everything you needed to play rock guitar.

This is the list to the best of my knowledge. Correct me if you know otherwise.

They are not in any order.

Riff Raff - AC/DC
If I Fell - The Beatles
Circumstances - Rush
Day Of The Eagle - Robin Trower
Heavy Metal - Judas Priest
Master of Puppets - Metallica
Little Dreamer - Van Halen
Strutter - Kiss
#2
Well, it's an informed opinion. But nothing more than that. Someone else could say, well, why learn 10 songs when you can just learn 3 Children of Bodom songs and cover it ALL. Fortunately, no one is going to learn those 10 songs and nothing else. What's the most recent of those songs, and has there nothing been developed since then? In any event, I'm not a fan of reductive approaches to learning something. "EVERYTHING you need to know in 10 songs" or some such thing.
#4
no one ever need to learn Wonderwall ever again and every copy of it should be destroyed