Welcome to the CPL Navigation question and answer forum. Please feel free to post your questions but more importantly also suggest answers for your forum colleagues. Bob himself or one of the other tutors will get to your question as soon as we can.
There is no such thing a the depth of the transition level. The transition level is the lowest flight level available for a particular flight. If you found reference to the 'depth' of the transition level please let me know where you found it - it is obviously incorrect. Are you sure you have not misread it?
This is where I’m a little confused, I understand the first question which relates to the QNH being 1004 which makes cruising at 11,000 not allowed but when the QNH is more than 1013 (1028) wouldn’t the lowest fl available be 11,000?.... the transition attitude is always 10,000 so that’s 1,000 separation...