Every week. It's pretty healthy and bloomed a beautiful pink flower in the summer so i guess it works for the plant
I usually leave him on the windowsill so he gets the light when the sun comes out. I've just found out through this helpful website that the sun may burn the leaves so they should be a healthy green colour. His leaves are healthy green but have a tint of red/pink.
I think light and water depend mostly on what sort of orchid you've got. Have a look,
Orchid Care Tips: Light