Our kitty is an outdoors kind of cat. Because of that, he doesn’t really mind being left alone, as he can explore, nap, or meet up with one of his friends. Our puppy, however, is opposite, and is like your kitten.
He follows you around because your his parent now that his natural mom’s gone. That’s why he crys so much when you leave. It’s best if you take some time to play with him. If you don’t have anytime to spare, leave chew toys for him to play with (helps with the biting problem, too, since young mammels need something to bite when teething). He’ll calm down after a while. When he’s old enough to neuter, do it, as he’ll be more relaxed.