Unless there is water logging en-route (in which case all the trains are bound to get delayed), this train will maintain its schedule. Also, do not worry about the ticketless passengers occupying your seat in AC Chair Car coach. That only happens in 2S (Second Sitting) coach. However, if you're not boarding the train from the originating station itself, then MST pass holders might occupy your seat. No worries at all if you're boarding from the starting station itself.