I am averse to the idea of loco reversal and slip coaches.They only result in wastage of time and nothing else,This should be done in areas where it is mabdatory.So trains which is running well should not have any slip routes.
My suggestions-
1.kolkata haldibari sf-no change,running well,upto haldibari its ok
2.UTTARBANGA,KANCHANKANYA-both serving nbengal and respective areas...24 coach needed.deletion of stoppages in SDAH-MLDT section,speed...
more...

up required,WDP loco link,not required to have any slip coaches and turn it into another teesta torsha.
3.The Y-LINK bypass can only serve DEMU or RING RAIL services only.
4.Better to have a KOLKATA-DHUBRI SF Exp and run it through NCB-NCBD-MAYNAGURI ROAD JN-JPE-NCB section,then it will cover all the areas.
5.Split Teesta Torsha EXP into two parts.TEESTA-Upto haldibari via the existing route.TORSHA upto New Alipurduar via behrampur,jiaganj(after completion).
6.AC EXPRESS to be jan shatabdi ....extend it upto NCB.stoppages only in nbengal ,no stoppages otside the region.HWH,RMPH,MLDT,NJP,JPE,NMX,DPG,FLK,NCB or VIA MAYNAGURI ROAD JN,NCBDMATHABHANGA(after completion and track upgradation).
7.RING RAIL DEMU to be started in various slip routes and the newly completed NCB-NCBD-MAYNAGURI ROAD JN-Y LINK section to connect all areas with the principle nodal points.
8.RING RAIL ROUTES-NCB-NCBD-y-link byepass-NMZ-APDJ-NCB
ncb-ncbd-maynaguri road jn-NMX-NCB,
njp-jpe-byepass-lataguri,nmz,apdj(DEMU PASS SERVICE/can be a convntional I/C too).
NCB-NCBD-JPE-NJP I/C service.