bro reading ur post while sitting in naran. came from karachi all the way so here are practical tips that i faced.
route as explained earlier by some1 KHI - enter N5 - Bahawalpur - Lodhran - Khanewal - Kabirwala - Shorkot -Toba Tek Singh - Gojra - enter M4 - M3 - M2 - Islamabad - Abbottabad - Mansehra - Kaghan - Naran
Few things regarding the route above, superhighway kci-hyd under constr. Route bypassing multan again not in good condition. Route kabirwala-Shorkot terrible condition. ahead of that u will love gojra n islo motorway(top speed mine 230km/hr in my reborn)
Route isloo-abt good although one way. Abt-mansehra-balakot under construction. Balakot to Naran again excellent with only 2 to 3 water and glacier crossings which can be manged easily.
staying places, hotel 1 at bwp. millinium hotel in Naran costed 4500 rs a night with all facilities like electricity, tv from 1830 to 0400 hrs, perhaps the best in naran but rates will surely go up after eid as it is ramzan so rates are down due to less rush.
documents u will need i think to be safe keep ur id card, driving license, car registration book, although i never required any of them through out my journey(maybe with family thats why)