Hi Arsalan,
Good to know about your plan. However, Plz keep in mind that Rush Lake is not a beginner trek. It can easily be classified into intermediate to semi-advance level trek. It will take you 3 days to reach Rush Lake from Hoper with camping spots at Day 1) Berchi kor 2) Chitin Hara 3) Rush Lake .. There you can also scale Rush Pari peak and then 3 days to return via Day 1) Phy feri (pronunciation??) Day 2) via Miar Glacier to a village, name forgot Day 3) Hoper
In this whole trek, there will be no water at many places and harsh weather (hot in day time and very cold freezing in night) and you will have to cross many glaciers and fast running streams. You will also have to hire porters to carry your luggage, supplies and water and should also have proper camping equipments and food supply.
I haven't done this trek personally. All the info I know was collected because I narrowly missed this trip in 2012 but my friends successfully completed it. They were 15 friends and only 8 completed till Rush Lake and out of these 8, only 3 completed Rush Pari peak trek.
If you're well prepared and have good physical fitness then surely go ahead. best of luck.