Centering the window : of course raine keeps as many coordinates as it can, it's since we added all these windows statuses which created so many problems ! So it knows where to position precisely a window when exiting from fullscreen to return to its previous state, but if the physical screen changed and now the resolution is not the same anymore, then it will mess things up. There's not much which can be done about it, it's obliged to reduce the size to stay in the screen, but then should the position be changed too and how ? For now it isn't touched, it's the safest way, it would really become crazy to try to adjust position when the size has changed too.
The black screen in windowed mode : yeah my fault, I didn't get the right values for the desktop resolution, now I ask the desktop resolution for display 0, hoping we will never handle more than 1 physical display because I don't plan to use more than 1 here.
autodetect sound all the time : yeah but it would force to have a special value which says "detect the soundcard but don't store the result, just stay in autodetect", so it's a little tricky, and not necessary in most setups, your setup when plugging a new dispaly changes the soundcard priority is quite original. And always detecting the soundcard is not a good idea neither in the case where you run without a desktop, which I do on the mini computer, it has a bare environment, no desktop, and in this case it can get some rather crazy value for the detected soundcard. Now I admit that if I was to use regularly raine on that machine, I would put a window manager, at least for fullscreen, here it's bothersome... !
Anyway since it takes you only a few seconds to adjust manually, it's the easiest solution for now.