i dont kno about hiace rental but i can tell u this.
Niazi leaves at 12:00 am night time. last year fare was 500 per seat. It will drop u off at mansehra at about 6-6:30 morning.
From there it's simple, taxi(mehran/carry daba) wll charge up to 2000 till shugran. Or u could take loacl hiace van, last year they charged 160 till naran, its same for shugran too. but in hiace u will need to take taxi up to shogran, they will take arnd 800 till top. So taxi from start is better if u want to go to shogran. And No u cannot visit siri/paye and get to naran same day, night stay in shogran is a must.
From naran jeeps are like this:
~2000 till saif-ul-muluk, round trip
~4500 for noori-top/lulusar/lalazar in one day(that includes diesel)
Babusar top will not be opn to cross but u can go to visit it, but it will take one full day for that, u cant combine it with anything eles, n
Noori top will definetly be not open to cross, jeeps might get u close, it will be on foot onwards, last year in july we had to trek 3 km to top, and i was difficult due to icy water flow and snow all along the way
u can get reasonable rent rooms, like 1800-2400 / room.
Beware: Its all about bargaining out there! u can save about 30% if u bargain well.
Also try to go during week days, much much cheaper, on average all prices go up by more that 50% on weekends to to higher number of tourists