About the wide crossing near Kelana Jaya extension station 2. I understand that is for the additional third track for storing trains, similar to thr third track near Kelana Jaya line University station.

A few notes ...
(1) KLJ LEP Station 2 is north of NKVE
(2) KLJ LEP Station 3 is south of NKVE
(3) Logical connection to KLJ LEP depends on which area (North or South of NKVE) will be served by LRT3
(4) Branch network usually doesn't make sense for LRT line where capacity are already limited by train length and frequency, because the two branches will always have half the maximum capacity of the trunk line.
(5) Limitation of branch network for LRT can be seen on RapidKL AMG Line: Chan Sow Lin to Ampang branch and Chan Sow Lin to Sri Petaling branch.
(6) So a branch from KLJ LEP to LRT3 even if possible at this late stage, may not make sense technically.

Yes, it seems.

Even when rolling stocks are different, there are still merits to transferability of other rail borne vehicles between two lines. I understand LEP AMG and LEP KLJ have track connectivity near Putra Heights station for direct movement of some rail borne vehicles between the two lines. Even when there is no direct track connectivity there are other means of moving rail borne vehicles between two standard gauge lines.

Comments to SPAD's KV LPTMP URDP (Urban Rail Development Plan) may be the best place to forward that concept ...
http://www.spad.gov.my/projects/national-m...-klklang-valley

As is, that URDP envisage in 2020 there will be 3 MRT lines and 3 LRT lines in Klang Valley.