Yes. The Leapers UTG AR15 Super Slim Fixed Low Profile Front Sight will match and align with the Super Slim Fixed Rear Sight from UTG. Optic center height will be an absolute co-witness, AR15 height, of 1.4".
The light pictured is the UTG 400 Lumen Compact LED Weapon Light. You can find that weaponlight using the following link:
https://www.opticsplanet.com/leapers-utg-400-lumen-compact-led-weapon-light.html
Yes, they are compatible.
This fixed front sight is able to be used with other of Leapers flip up rear sight posts.
Co-witness is determined by the red dot's mounting height. This is a standard height front sight so as long as the red dot is mounted to an absolute or lower 1/3 co-witness it will co-witness.
It will work with a carry handle if mounted on picatinny rail that is the same plane as the receiver. If mounting to a gas block where the picatinny rail is lower than the receiver you will want the following sight:
https://www.opticsplanet.com/leapers-utg-ar15-super-slim-fixed-high-profile-front-sight.html
This is designed to be mounted on the same plane as the rear sight. Here is a link to a gas block height version of this front sight:
https://www.opticsplanet.com/leapers-utg-ar15-super-slim-fixed-high-profile-front-sight.html