Your first question is best answered by SCR only :)
As far as crossings are concerned, there are crossings by SBC-KCG, MS-KCG, KSK, SBC Raj, Venkatadri and OT by Venkatadri and Padmavati. And usually more priority is given to KSK, Raj and Venkatadri during these crossings/OTs. And until recently Pagidirai was only crossing point available between GY and Pendekallu, so slack was provided to make up for time lost in waiting for crossings.