Hey Gaurav,
Places to see in manali for 2 days :-
Hidimba devi temple ...
Manu temple ...
Mall road for shopping or even window shopping ...
Vashishta temple is also a must visit ...
One more day you have to leave early to ROHTANG pass to enjoy .... and if the pass is open ... that's difficult to say now only ... check with your hotel guys before two days of your travel and get the perfect picture and make any changes accordingly ...
And enjoy in Kasol for 2 days just resting Bro .... just enjoy the weather and hills of Himalayan ranges ....
Always best to take a hostel ..
And few reputed and dependable hostels are :-
1. The hosteller Kasol -
The Hosteller, Near Kasol Temple, Old Kasol, Kasol, Himachal Pradesh 175105
https://thehosteller.com
09810187717
2. Nomad's hostel Kasol -
Village Chojh, Chojh Bridge, Manikaran Road, Kasol Road, Kasol, Himachal Pradesh 175105
http://nomadshostels.in
07807909245
Happy and safe Travelling Bro!!!
Day 1 delhi - kasol and go and stay manikaran gurudwara
day 2 keep your bags at manikaran and come to kasol and check out kasol and chalal and go back
day3 catch early morning bus to burshaini last village and do kheerganga trek either come down same day or stay up and come back next day
day 4 check out tosh malana
4 days not possible to cover manali