Commercial pilot requirements & training questions

In the next few months I plan on getting my commercial single engine
land and multi engine ratings. I'm totally baffled by the aeronautical
experience requirements though.

FAR 61.129 is pretty clear that SEL and MEL each have required dual and
solo cross countries and night flight. However I have read in this
group, and been told by my CFI, that you don't have to do the ME cross
countries if you are doing it as an add-on to CSEL. Where is this
documented?

I was also told that you don't have to do the instrument training
portion of the CSEL if you are already instrument rated. I would like
to believe this but don't see how it could be true.

Finally, any thoughts about the least expensive and fastest way to get
CSEL, CMEL, CFI, CFII, and MEI? I have about 200 hours, PPL (ASEL)
w/instrument rating.