Which road to Leh is less busy (during summer), via Srinagar or via Manali?
You will find less traffic on Manali route because majority of commercial and defense vehicles use Srinagar route which is also a better quality road.
Do both routes have places to eat and hotels en-route if we decide to stay over night somewhere in between to break our journey?
Srinagar - Leh route has a lot more options as compared to
Manali - Leh route for both accommodation and places to eat. Manali route does not have as many petrol pumps as Srinagar route does. If you do go via Manali, the only large town (not so large) is Keylong and that is the only place in addition to Sarchu where you can find decent accommodation. Srinagar route has plenty of places to stay.
Are tourists allowed to go via Srinagar and come back via Manali or vice versa? I believe there is some record keeping done by Army on both the routes hence the question.
Yes you can.Those records are kept in case they need to track a vehicle, not to prevent people from using the other route on their way back.
Although we are planning to go on motor bikes but if we decided to hire SUVs and took our own tents, are we allowed to pitch tents on either of those routes and also at Leh near the lakes?
You can pitch tents near villages by talking to villagers and paying Rs50-100 or whatever deal you can make and that's the price with tea shops as well who would let you pitch your tents near by for a charge. At Leh you cannot pitch your tents near any of the lakes as that is not allowed so don't even try, Pangong lake is of religious importance (and other lakes too) to locals and I won't be surprised if a taxi driver picks up a fight with you if he sees your tents anywhere near the lake.
Tso Kar lake has a tent accommodation available but tourists are not allowed to bring their own tents so renting their tent accommodation is the only option.
Is it possible to send motor bikes from Leh to Delhi should we decide to take a flight back to Delhi on our way back?
Yes, a lot of people do that. You just need to ask at bike rental places who to contact.
Is it advisable to be out on the roads at night on our way to Leh and also for sight seeing in case we want to stay upto 7-8ish at one of the lakes?
Leh is a crime free area and when you are in a group it is not something you need to worry about but generally speaking it is a good idea to return back to your hotel before it gets dark purely because roads are not the best and could be dangerous to drive at night.
What is the crime situation like at Leh and en route? Is it safe for tourists especially when we would all be from Pakistan? I have been to India before but never been up north.
You should be more worried about getting a visa than anything else. India is a very tourist friendly place and people in hilly area are known for their helpful nature. Take the Srinagar road if you are too worried but it is safe otherwise. Just use common sense really.
