How do I take care of my new kitten? Why is he acting the way he is?

That's very considerate of you to be worried for your new kitten. My cat, who is about 7 or 8 years old today does a lot of those things. When he's meowing loudly for no apparent reason, does he have a toy in his mouth? My cat does it because he wants to show it off or he feels lonely and wants a companion to play with. Does he have buddies he can play with? Cats love attention from their owners but sometimes it's nice to have another cat to run around the house with. There is no right time for this and for that. You're right to not want your cat to become huge because it's horrible on their paws. Be sure to limit his intake by giving him a small bowl (a little larger than his head) and only refill it once a day depending on how much he eats and how fast he consumes it. My cat goes ballistic for no reason and starts to bite whoever is playing with him at the time, but honestly, that's just a cat for you. The thing I do is tell him to stop and when he releases, he'll jump down and go about his business like normal. Kittens love to be played with, so play with him as much as he likes. But sometimes, you have to step away and let them nap or groom themselves. Cats who mew loudly and randomly want attention. So if he's got a toy, ask "Milo, is that for mommy? Is that toy for me? Come here, let me see what you've got."