Buy a Surface Pro 3 and use a wireless keyboard/mouse. That's more or less what you're asking for. I will admit you'd need pretty heavy duty velcro to attach it

Buy a Surface Pro 3 and use a wireless keyboard/mouse. That's more or less what you're asking for. I will admit you'd need pretty heavy duty velcro to attach it to the wall, but it likely is do-able if you don't mind having a completely fuzzy-backed SP3.