The camping at triund costs around 1200 - 2000 rupees, depends on your preference.
Jaisalmer is on the west end of India and Kolkata is on the east end of India so the journey is quite long, prefer a train/airport
See the tour listed on things to do a section of Udaipur
if you want a relaxed trip, prefer 2 days at Jaipur and visit the three forts on day1 and city side on day 2 of Jaipur
you can go to Solang Valley, Vashisht temple Manali(hot spring)
you can go to Manikarna, Kullu which are near to Manali
yer there are many ATM's on the airport on Delhi
I think this hotel might be a scam. I would recommend that you don't share this with anyone.
The pollution is not bad this year. It is getting settled and it would be over in the next 3-4 days. Still, monitor the air quality scores.
When traveling solo always prefer hostels as they affordable but also get the company of other travelers.