Do note that our adorable Hitsugaya is a midget, not a little kid. He's pretty much an adult. Just younger than all the other captains. And Karin is like what? 11 years old? Please don't make poor Toshiro look like a pedo. I know Karin is 13 years in further episodes but seriously?
I'm not really sure about the HitsuXHina thing. They're childhood friends. Pretty much treat each other like brothers and sisters. Nothing lovey dovey going on.
HitsuXMatsu? OH YEAH BABY<3 DEM BEWBIES. Get some, Hitsugaya!