Re: khi <-> isb (via bus)
Train all the way. You can walk up and down, meet people etc. In a bus you'll just sit cramped and unable to do anything. Khi - Isb is a long journey and you will appreciate the freedom of moving around. Plus at every stop you have those lilttle kids selling boil eggs and cups of chai through the windows :D
Seriously bus doesnt even compare to train. If you want an adventure, train it is.