Nikon Coolscan V ED JPG Compression Quality / or TIFF

I recently acquired this scanner to digitize my 35mm and APS collection
of negatives. At 4000dpi with JPG compression set to highest quality
my files were averaging 38MB per neg. I then read on some NGs that the
best format was TIFF since it is lossless. While I agree with that
statement I honestly could not see a difference in quality on my
Samsung 1200NF 22" AG monitor. I decided to scan a neg and save it
both as a JPG (highest quality) and TIFF. The JPG again was
approximately 38MB while the TIFF was approximately 68MB; a big
difference but understandable since the TIFF was not compressed.
However, I then opened the JPG in Photoshop CS and saved it under a
different filename as a JPG (highest quality,12); with NO changes. The
new file size was 16MB. My issue then is I will eventually edit these
files and resave them in Photoshop CS. When doing so, the TIFF will be
the same size and quality while the JPG will be signicantly smaller and
possibly not of the same quality as the Coolscan JPG and definitely not
the same as a TIFF. My question then is:

1. If capacity is somewhat of an issue and none of the negs are
professional, will the JPG quality of the NIKON Coolscan save be a high
enough quality for future editing as long as I do not resave to the
same file? And, will the Photoshop CS JPG as good as a Coolscan JPG?

2. Why is the JPG compression of Photoshop CS so much more than
Nikon's Coolscan software?

3. Should I forget JPG all together and just use TIFF?

50 rolls with 24 exposures will result in 84GB TIFFs or 43GB JPGs. I
have a server which stores my data and I guess I could always add more
drives. It would then be a matter of backing-up the data which I do
daily to tape.

Thank you