I do not have my book handy and am not sure what the current ruling is...
I know a few years back it was:
If a 6 year old registers, they can play coach pitch "provided they had one year in Tee ball"
So if a 6 year old never played Tee ball he must do one year of Tee ball before he advances.
The answer is yes, at 6 they can move to coach or machine pitch provided they had one full year in Tee Ball. III (c)
Yes BUT !!!
It's really up to the local league BOD.
They can decide to keep 6 year olds in Tee Ball even if they played as 5 year olds.
They can NOT allow a 6 who had not played Tee Ball to move up to minors.
can a 9 yr old try out to play on the major teams, if he hasn't played at least one year in minor?
Again, the answer is, it's up to the BOD !!!
That is, the BOD decides on the ages in majors so it might not let ANY nine year olds in majors (it could limit majors to 10-12 or even 11-12).
If the BOD allows 9 year olds in majors there is no LL requirement that a 9 year old has to have played a year in minors prior to playing in majors (then again, maybe the BOD has a "Local Rule" against it!!!).
A 6 year old can have a coach pitch to him in the T-Ball Division. He can't play coach or machine pitch MINOR division until one year of T-Ball which might actually use a coach pitching and/or the T.