Thanks for the replies guys!
Took a trip to the pet store last night, and picked up some wet food (Felidae! Funny you mentioned that, Carina!) & some laxative/hairball medication.
I'm going to increase the water their getting by feeding wet food a few times/week, and I also add warm water to their dry food in the evenings. I figure I could give the laxative to the longhaired cat a couple of times/week, and the kitten a small bit once/week. Hopefully this will keep everything "moving".
As for the Addison's - I think(?) that it has something to do with an underactive Adrenal Gland (so I think that means that it's not producing enough adrenaline?). Either way, I think that the vet may have put that "slight possibility" in the kitty's medical records.
Anyways, I have to pay off the existing vet bill first before I start paying for insurance.
I'm really hoping that there's no underlying problem, but I have a bad feeling about it. The kitten definately has less than stellar breeding (his mom just went outside, came back pregnant... his brother could possibly be his father!
) So...... genetics definately aren't in his favour!
Thanks again for the help!