Insects.
That would depend on which species of bat, you were referring to. Some bats eat insects, some eat fruit, some drink blood, some drink nectar and others eat fish and frogs. There are many species of bat each with different eating habits.
They have a sonar and they use it to catch prey
Yes bats do have teeth to suck their prey with!
Some types of spiders prey on bats.
By echolocation
both
no
No he wants to
Bats use echolocation to locate and catch their prey. They emit high-frequency sounds that bounce off objects and return as echoes, allowing them to effectively track and capture flying insects in mid-air. Bats have well-developed wings and maneuvers to chase and intercept prey during flight.
Birds of Prey
Echolocation
First, bats are not blind. Contrary to popular belief, scientific facts have shown that bats have poor eyesight, but aren't blind. Bats use echolocation. The bat emits an echo, or 'screech', then the screech bounces off of the prey, and then the bat hears the screech that bounced off from the prey, and then it catches the prey.
Both. They do act as a predators on other animals but also are hunted as prey.