It is a bulb. You just screw it in.
It detects motion so it will turn on when it you walk by or towards the light.
I would recommend the light being installed in your bathroom but not in the shower directly to avoid a lot of water entering inside! The light takes batteries so it wouldn’t do well with contact with water!
Yes, Mine is installed on the ceiling of a closet and comes on when I enter the closet and goes off when there is no activity for about 90 seconds. It can be wall mounted and to change the batteries, the housing must be turned which would be very hard for most toddlers. Keep it out of reach.
It twists off the mounting plate and back on easily for battery replacement.
4 D-size batteries
Yes it can be mounted sideways. It has a small anchor plate that has the holes to place where you need it.
Inside the light housing. There is an access cover you remove to install the batteries.
I would say yes it seems to be very sensitive
It stays on approximately 1 minute, but you only need to wave your hand and it comes right back on