does a centipede have the ability to only use one leg instead of all of them?

Answer 1

No, not even close.

Centipedes (meaning hundred-legs) have one pair of legs for each segment (or most of them) after the head. There are maybe seventeen or so segments with legs in an adult centipede.

A centipede trying to drag its body using just one leg or even one pair of legs, could be like a human trying to drag its body using only a finger or toe. Not possible. No animal adapted to life with legs (no matter how many) can survive without legs or with just one, except through human intervention.

Some animals (worms, snakes, blind snakes or blind worms, fish, some insect larvae, etc.) have no legs normally. They get around well because they are adapted to life that way. If an animal loses one leg (even if it has several others) it needs to learn to function with less legs.

Spiders are unique in having the ability to grow back legs that were lost. This is true of true spiders (water spiders, silk spiders, tarantulas, wolf spiders, orb spiders, etc.), not of sun spiders and sea spiders. This means that a spider does not need to be without some of its legs for very long.

Answer 2

No, they are linked by the nervous system.

Answer 3

I don't know, but you sure made me wonder about their toes!