9/8 beats are based on eighth notes. The ninth measure you mentioned is correct. It consists of three groups of three octaves, ***9 beats.

You can think of this bar as a 4/3 beat, and then think of each beat as a 4/3 beat bar. Sing it out: bang, bang, bang, bang, bang, ***9 beats, that's it.

I was wrong about the above paragraph!

The fourth measure is 7/8 beats. That's right!

The fourth bar can be regarded as a combination of a bar 2/4 (or 4/8) beat and a bar 3/8 beat.