Roof rack questions

I've seen a few posts about roof racks on the A3's but I have a few questions that didn't seem to be addressed in them. I'm particularly interested anyone that has first hand experience with a Thule system on their A3 with the Open sky system.

I posted some pics about removing the rear bench to get my bike in the back standing up to aviod having to use a roof rack, but I'm moving this summer and I will need roof space and trunk space to get my life across the country.

So...my questions are:
Is it possible to use the Thule farring on a car with Open Sky and will the roof still open?

What is the increase in noise/reduction in gas milage like?

How is the fit on the door sils and have you had any problems with the doors leaking or the rubber gaskets on the outsides of the doors getting stretched out?

Thanks