Karachi to Bahawalpur is doable in 10 hours so no need to leave too early unless you have any specific time to reach Bahawalpur.
When you reach indus highway it will be day light so should not be any concern.
You will need to topup fuel around Moro so it should be good time to take a break or as per your need.
There are no issues of kachay ke daku on this route and offcourse you should take M5 route.
Tyre pressure should be per specs of your installed tyres.