Yes. They work without a dimmer.
Twist. On mine I had to put quite a bit of pressure on the surface of the old bulb with my palm and turn to the left about 1/4 turn and they just fell out.
Thank you for the question. The lowest Kelvin temperature offered is 3000k.
If you are concerned about wasting watts out of the split reflector, I would say the effect is so subtle that you probably would not be able to tell the difference between split reflector and non-split reflector. If you have fixtures with pretty shades, the split reflector does a nice job lighting up the shade a bit. If the bulb is buried in a can or recessed fixture, it's sort of a wasted feature.
As long as your range hood uses the 120V GU10 bulb. Be prepared, they throw a lot of light.
No, they're direct lighting
It is doubtful you have to disassemble the fixture. Generally these lights just "twist and lock" into place. Get a grip on the edge of the blub and turn left to remove.
Need to see if your item will except the new bulb. also I had to ask for help at first at store. All new to me though