Hey,Check my tripoto blog on how to cover parvati valley in minimum budget.I can assure you after reading that all your doubts will be cleared. If you have any query even after that,you can ask anytime..
You can come back from Rashol and kheerganga trek on the same day if you start early morning. But one tip from my side,If you are going to kheerganga always do night camping there.Try to cancel your one day booking of the hotel..
Kheerganga Trek and trek to Tosh are best for 1 day. If you can spare 2 days opt for Malana or Rasol. If you ask which of these is most beautiful, its hard to pick, as all of them are unique and mesmerizing. Enjoy your stay at Kasol... I love that place <3
The trek from Kasol to Chalal will take 1-1.5 hour. For other treks you can go to Magic valley, Weichin. You can explore places like Manikaran, Tosh, Malana and Rasol.