The consistency is fine, Elocin .. when we first got our little guy, he would go absolutely anywhere ... but training him was not a problem: I don't think it took us a week to have him poop in his tray (he now has two)

I don't know how often you should be feeding them .. it sounds a little much, but we feed our guy (he's 7 now) 3×daily - kibble at 0600 and 2130, and canned stuff (usually a pouchful) at 1800 .. I would look at the side of the packet / can to see how much you should be feeding them.

As for the tummies, if you're concerned, talk to the vet about it. When both our guys were growing up, we'd be at our vets almost constantly .. that's what they're there for! Just like with real-kids, you can never be too careful!