Based on my personal experience of travelling with family, following are my responses to your questions:
1) The road from Sukkur-Hyderabad is pretty safe these days, however its best to travel by early hours of night and avoid late night travelling.
2) The police is notorious, no matter how complete your documents are. The best way, IMO is to talk to them with confidence, if the car is in your name and you have all the documents including road insurance and highway code book you should be OK. Still if there is a problem, a couple of local red bucks would certainly help. Its like a road tax.
3) I think no issues
4) No special precaution just usual ones that you undertake while driving on highways
5) You will find plenty of details on this on net / Pakweels. Sea View and Mazar-e-Qaid should be must. Rest plenty of options for eateries, shopping etc. There are are plenty of sea-side spots along the sea belt like Manora, Hawksbey, Sandspit, Paradise Point, Mubarak Village etc.
I hope this is helpful!