Yes. But only after an ecological assessment shows they could survive.
No. Man is part of the ecosystem and the extinctions are therefore natural and should be permanent.
If human beings are the reason for their extinction, then we have to take responsibility to resurrect them. Also need to take care that, cloning doesnt add some unwanted or unexpected issues, later on.
My only fear would be that the species that was brought back to life would wipe a different species out, couldn't survive anymore naturally or through the cloning, become less than what the animal truly was.
No. Firstly, there are many problems with cloning that could cause harmful mutations to the animals. Secondly, reintroducing animals incapable of living in our current world is futile, since they already died out once and therefore will likely die out again. Finally this is only a band-aid solution as it addresses the effect, not the cause.