Not a lot that can be done about the sun hitting the display I'm afraid.
I've only just recently seen some pictures of the Xenarc (I think they're all universally bad to be honest) and I was hoping it would be equivalent to an Alpine or Pioneer touchscreen, but it's terrible. Your only solution really is a transflective upgrade/screen - which, unfortunately, is quite expensive at the moment.
Sounds like you have the M1-ATX misconfigured if its not automatically powering on the system.
You have to expect teething problems to begin with to be honest. Expecting it to just drop in like any aftermarket system is a fallacy really.