Though your question doesn't contain sufficient information but what I can understand you want to travel from Delhi -> Agra -> Rajasthan -> Western (Mumbai/khandala/Pune/Goa) -> to Eastern (Calcutta).
Yes you are right, its very easy to meet people in India but to meet right people is bit sometime. You will be flooded with Tourist guides at every location (most of them are fake/local, don't know much about the place). Its always better to contact Government tourism officer rather than saving few bucks with local adviser.
In India, Hostels are not much preferred because you can get a cheap hotel very easily. Hostels are also not well equipped, don't go for it (Keeping your money concern in mind). You can easily get good cheap hotel in some Rs 1500-2500.
For long distance travel like from western part to eastern part (Calcutta), don't forget to book flight ticket in advance. Trains are always running over booked on these routes. By road, it could be tough/hell time consuming. But yes Northern (Delhi) to Western (Mumbai) part is well connected with Highways and expressways.
If you have time don't miss - Leh, Kashmir, Shimla, Manali, Nanital (Northern India part).
In western part - khandala, Lonavala, Shirdi (if your religious), Goa. Plan in advance.
Don't forget to bargain in India, you should easily bargain for more than 50% at local shopping places as well as in hotels, private cabs etc.