Depth Levels of File Subdirectory Tree Allowed.

I have my hard disk organized into several volumes and directories in each
volume as normal. In some cases I have several levels of subdirectories,
perhaps 7 or even up to 9. I have not had problems in creating deeper level
subdirectories. I have not tried more than, perhaps 9. But I am not sure how
many I have at times. This leads me to my first question.

1. Is there software out there or some function in Windows Explorer that
will let me know how many levels deep is a subdirectory?

2. How many levels deep does Windows Vista allow? Does this differ from
Windows XP?

3. I often back my files to data CD's and DVD's. There seems to be a finite
and lower number of levels of subdirectories allowed for the CD or DVD to be
readable? What is this number? How can one make sure that one is not writing
a subdirectory that is so deep that the DVD/ CD will not be readable?
(Roxio's software gives a warning about this for data CD's but have not
noticed it when writing data DVD.

I have searched for this in various places, but something this obvious seems
rather esoteric knowledge.

I would appreciate someone who can help out. I am specially interested in
software that will tell me
a) the number of levels deep in subdirectories that I have and if there is a
problem.
b) the length of the file name, which I believe includes the levels of
directories and subdirectories in which it is embedded. I could be wrong.

Thanks.