1) Do i can use the same apps i use on tablets and smartphones? You know, social networks, office suites, google drive, MX Player, wikipedia and others?
They all work
2) Is it possible to connect a keyboards, mouses, USB sticks and USB HUBs through a OTG cable?
From what I've heard, yes.
3) Does the streaming works with most Windows games or select games only? The games can only be streamed through WAN, right?
Controller compatible only, unless you launch it through the Steam browser, functionality is not guaranteed. Yes, WLAN.
4) Is it possible to install APKs? I want it for testing the apps i am developing.
Yes, same as any Android device.
5) Does it feature a accelerometer for certain games (Like Infinite Flight) or some kind of way to emulate it?
6) Is it possible to play games that use MOGA controllers? (Asphalt 8, Block Story)
Yes, if the controller is not supported by default, you can download custom mapping made by users by long pressing the "start/play" button.
7) Is there some app i can use for stream the Xbox 360 to Shield?
I... I would think it's feasible... You would need a fast capture card, really fast,, like no delay, and a USB prog device for the system.
8) How much i can play while not in charge?
I've gone 5-6 hours running 3D intensive games and about 7-8 hours running regular apps with maybe some music.