i thinks its more than 6 hrs to kel, around 4hrs till keran, after that road is not in good condition. Also depand on ur vehicle and driving style, and how much u stay in between, without rest its difficult to cover so much distance
stop over will be at dhani waterfall on the way, then Keran, and upper neelum (upper neelum is off the road) , then We also stop at sharda, we stop for few water nalas for sight seeing and tea with snacks.
If u r travelling in August no need advance booking in arang kel, Lot of guest houses in Arang kel, also summer vacation is over,
We stayed in Arang kel residiency 0312-9000674, 0355-6604284, 0347-5341177.
Best regards