2. We have full freedom to wage proxy war. Nukes bring stalemate to conventional conflicts, not proxy wars. It is our own shortcoming that we did not engaged in proxy war in Pakistan ,even though we have resource advantage over them. Here you should blame "cowardice" of common Indians ,which percolate to politico-bureaucratic elite of this country. BMD would affect this due to psychological effect it would have on Pakistanis. If they believe that Indian BMD works, irrespective of whether it work or not, they would not be sure whether they could contain their war in domain of proxys.
4. That's why I said "economic strength" ,not "scientific advancement". Pakistanis ,by not investing in basic S&T and preferring to import and repaint their weapons, have falling far behind India in S&T (Even India is not best in the world, but that only serve to demonstrate the length to which Pakistan has fallen) and thus could not compete head on with India in this field; but option of buying from China exist, but degree to which China could help them depend on economic strength of Pakistan. Even China has limits to being sugar daddy of Pakistan, specially when India could retaliate by arming its neighbors.
Another point related to this is that even Chinese would not be sure of ability of their countermeasures to defeat a BMD, let alone Pakistanis. When people criticize BMD for not providing a guarantee that it could intercept 100% on missiles, they ignore that other side (countermeasures) also could not provide a guarantee that they could get through a BMD. This would not matter in case of Russia and USA where you have thousands of nukes, but in case of Pakistan ,where you would could have around 200 nukes. Pakistan could not indulge in nuke spam tactics of USSR as they do not have access to Uranium mines of Kazakastan.
6. Seeking options is a prudent thing to do in a war, and every logical person would like to do that. The problem with nukes is that, if your enemy too have them, they lose their fear value as after a certain point, you are sure that you could affect your enemy's behaviour due to mutually assured destruction. If you want to break this cycle, you would need defensive technologies to complement your offensive nukes.
You cannot compare restricted technologies with consumer technology where fall in prices is given. The counter measures to BMDs , could not only be countered easily, are expensive but they reduce efficiency of missiles themselves.
(1) First: A BMD interceptor missile has kinetic advantage over a BM as an interceptor missile has to only gain intercepting altitude, while a BM has to leave atmosphere ,attain apogee and then came back. This mean that any increase in weight impose larger penalties in BM missile than on interceptor; and every counter impose weight penalties.
(2)The so called counters of BMD are duds. (a) Dummy warheads: Algorithms exists at predict path of warheads and could thus differentiate between dummy and live warhead. (b)Balloons and chaff: Not effective against modern radars (c)Maneuverable warhead: a realm of fantasy as maneuverability is inversely proportional to square of velocity, and if you reduce speed to make your warhead maneuverable, it become easy to intercept it.
This is the reason why you do not listen about test of counters too often. Countries like Russia have given up on them and are focusing on monster missiles (RS-28 Sarmat) which could carry upto 20 warheads thus overwhelming BMD.
How much reserves? How much of that is mineable? What if U-235 % on those reserves)
Even by most optimistic estimate of 600 tonn by your own source , you would only get enough fissile material for 36 nukes ,even if you convert whole of your Uranium reserve into fissile material and maintain 100% efficiency on all stages starting from mining to machining.