What was or wasn't true in the film "Walk The Line"?

SPOILERS BELOW!!! STOP READING IF YOU HAVENT SEEN IT!!!

That seems like a terrible way to ask a question- oh well. I’m curious for anyone who knows about the life of Johnny Cash- what events in the film were not true or changed for dramatic effect. I just saw it for the first time (I know) and I loved it, actually. But some events seemed more difficult to believe that they actually happened that way.

Sub Questions:

1. Was there really a tour that included Jerry Lee Lewis, June Carter, Johnny Cash, and Elvis. (was Buddy Holly there too, thought I saw him?)

2. Did he actually walk to the Carter house from Nashville?

3. Did he collapse in front of the house he bought on the lake?

4. Did he really write “folsom prison” when he was in the air force based on seeing it in a newsreel.

5. Did his brother die in an accident with a saw while he went fishing?

Ahh there are a few others but that’s probably good for now.