New Sheild tablet-Game recordings topic

Hi, i've just bought a shield tablet after getting absolutely sick of my galaxy tab s 10.5's lagwiz. Few questions i have.

I've been tinkering with screen capture, the files are stored on my 64 gb sd card but i am not able to delete the files. How do i do this? Can i choose a custom save location?

The power button is horrible, is there any way i can install a double tap to wake like feature without rooting?

Thanks