Regarding the interception of cruise missiles, in general, it's a sketchy proposition. Leaving aside decoys, which competent forces would use to saturate Air Defense systems, cruise missiles are exceedingly difficult to detect due to an inherently small RCS and no active emissions for the majority of the flightpath. So interception is a long shot, especially over land, in their terrain-following phase. Even for AWACS overhead it would be hard to track CMs against the clutter, even on flat terrain, and the Himalayas are anything but flat. It's great terrain for masking cruise missile attacks, although their range would suffer. This problem is only going to get worse for the defending side with time, as hypersonic missiles and glide vehicles come online.
The best way to defeat cruise missiles is to attack their launch platforms and cripple the enemy's C4I networks, before they launch them. If the enemy launches first, be prepared to take the hits. Even if some are intercepted, most will be expected to get through. All of this works against India. The few cruise missiles they have aren't enough to stop a multi-dimensional Chinese onslaught, and I fully expect that if war becomes inevitable, it will not begin on India's terms. I'll stick to my assessment from March/April though, posturing aside, there will be no war anytime soon. We are in the set-up and positioning phase.