PGT-PGTN is BG from long time.. As far as from my memories it was BG+MG..
And in PGT, the old MG station(PF 1A) has rebuilt for 21 coaches, which will make no of PF to 5. Guess it will be commisioned along with PGTN-pollachi section.
Yes, rake reversal will be required for KR trains, if any. It wont be issue