Correct according to the old tech book, but the new technique book gives more options than this. When taking your exam, you should find out which book your examiner will be using, and study accordingly. Nowadays any official ISTD professional exam will be conducted based on the new technique, however on the "unofficial" studio level you may still find people who prefer the old method, so it is always best to ask in advance.

Regards,
Jonathan Atkinson

First step is considered ball, although you can lower the heel or even make light contact with the floor. Just don't drop weight onto that heel. In other words, ball or ball-flat is fine, the stipulation being that the "flat" is only light contact with the floor.

The second step is considered ball-flat, although the heel may not necessarily lower completely, particularly at faster tempos.

The third step is definitely considered ball-flat. The only exception to this might be when you turn on the foot, in which case the heel would need to be free of weight. You could therefore dance ball or ball-flat.

Wow! All these options! You can therefore have B-B-BF, B-BF-BF, BF-B-BF, or even BF-BF-BF, depending on context. And if you turn on the third step, you can also add these options: B-B-B, B-BF-B, BF-B-B, or BF-BF-B. Complicated, yes, but it will make more sense as you get used to it.

The inside edge of foot your teacher is talking about is fine; this is caused by the rightward hip and flexed left knee. The technique book doesn't discuss the inside edge, but it's going to be more prominent on some chasses than others, so I suppose they were trying to keep the definition broad to cover all types of chasses.

The brief moment of time when both heels are up is not absolutely necessary as per reasons discussed above, but it is within the realm of possibility. I don't want to get in the way of any particular concept that you'r teacher is trying to get across to you, so my advice is to follow his/her instruction.

I hope this helps.

Sincerely,
Jonathan Atkinson