Presently their main focus is giving "Great travelling experience". All things you mentioned are time consuming and many times expensive than cosmetics of coaches. If they are planning to increase speed of 2 of the busiest routes from 130 to 160, and it is going to take 4 years (minimum), IMHO they should aim for 200 and start working on that. Of that Delhi-Kolkata route is mostly flat and straight while Mumbai route has some steep inclines between Kota-RTM but otherwise flat and straight. Under station development, they should build waiting halls on an upper deck and with multiple exits connecting to at least 2 FOBs so that whenever passengers know which platform their train is arriving, they get there easily.