Yeah I agree with
@Meoncoast that (when you're thinking of the pop-up-roof) rain really isn't anything to worry about, unless perhaps it rains days on end or the rain is part of a storm, when really wind is the real problem. Although some people might be woken up by the sound of rain.
I have only once chosen to lower the roof because of wind. It was recently and the winds were 8 beaufort (40 knots, 46mph, 74kmh). It helps when you turn the roof with the lower part (back of the van) into the wind.
Of course the roll-out awning is something to keep an eye on. Make sure it's tied down well and if it does rain a fair bit, make sure one of the legs is set much much lower then the other. If it rains really hard, you'll want the awning to be quite diagonal to really allow the water to flow out. In some cases consider winding it in (especially with strong winds). We never leave the van with the awning out and never go to bed with the awning out if there's serious winds or rain coming. (came back once to find the awning trashed because rain build up).
It's ok to fold the pop-top down when wet, but a good idea to give it a chance to dry when the rain stops.
We ventilate by using the ventilation roster that goes into the sliding windows. Under the awning rain usually won't come in and often rain comes from either the back or the front so you can also use the roster in the other other sliding window. (kitchen)
Drying stuff inside the van is not easy. Raincoats and wet shoes go under the awning and under the van respectively. You can dry stuff (shoes, clothing) when you place 'm in or above the doorstep at the sliding door. The heater can help to dry it and if anything leaks,` its in the doorstep.
Take shoes or boots that you can get into and get out off very easily (no laces, etc) so you can leave them outside the van. Make sure you think about where you pack stuff so you dont have to go out into the rain a lot (tail gate access) Bring games or books or alcohol ;-) and have fun