My 9 weeks old kitten meowing ever so often.?

I just adopted a 9 weeks old kitten a few days back. He's now doing great at making himself at home. However, I'm worried because he doesn't seem to eat much. He does eat but not as much as a normal kitten down. He eats less than half a kitten size wet food can sold in pet stores, which is only like 2 tablespoons of wet food a day. He doesn't drink much either despite I change his water bowl everyday.

He's really active, playing jumping running here and there all the time. But he has been meowing constantly that it worries me. Whenever he meows, i would play with him or pet him or talk to him. He would respond to me perfectly fine but after i stopped paying attention to him for a few minutes, he would start meowing again.

I have work & will probably be home before night. Usually I would put him in a 3 tier cage with a litter pan, food, water, toys & blanket. I don't want to let him roam around the house alone just yet as I feel that it would be dangerous.

Any advise on what could be wrong? Could it be that he's lonely & wants a friend? I am considering to adopt another kitten around his age but if there's a solution to this, I wouldn't want to adopt as I dont want my attention for him to be divided.

THANKS!