Do you mind me asking what brand of food you're feeding him? My opinion: supermarket brands like mon petit and Whiskas are somewhat addicting because they're like junk food with higher levels of salt and additives. Can you even read the ingredients label on these cans? (In the case of mon petit, probably no.) Fish can also be very addicting to cats, and, as far as I understand, not a "natural" diet for cats (i.e. cats in the wild wouldn't go and eat fish... ). Generally, cats shouldn't be eating a diet solely of tuna as it lacks the nutrition they need. (Sorry, while I'm at it, I also believe there are some serious sustainability issues with overfishing and seafood, and I'm sure the fish going into cat food isn't the most sustainably fished and might even be coming from trawling or other destructive fishing practices.) I've also read animal byproducts is not the best ingredient to be feeding a pet. It's good to provide some wet food in their diet to help avoid a urinary track infection (usually only happens after the cat is older than 5 years, but be very careful with male cats and this can lead to a very serious condition!!!).
For a kitten: yes, they should have as much food as they want until they're fixed when you'll then have to monitor their food. I think what you said is fine... leaving dry food out at all times and feeding a couple meals of wet food.
Getting information: Do some research on good nutrition and good brands. I personally feed our kitten and cat Orijin dry food and Applaws wet food (only chicken is the ingredient). This is a pretty expensive diet, though...
Be careful about how you get information, because the pet food industry is pretty confusing. A lot of brands like Hills or Royal Canin sponsor organizations like the SPCA (which is fine), so just because they're selling their food or giving it to you when you adopt doesn't mean it's the best. You'll notice many of the Royal Canin dry food packs has "maize" (=corn) as the top ingredient! Websites, too, may be run by or sponsored by these major brands. It's a major industry and not regulated as well as our human food (or at least regulated differently in all these different countries...).
Be careful, too, about the order of the list of ingredients. Generally, the ingredients will be listed from top to bottom from the biggest percentage they consist of (e.g. chicken 75%, chicken broth, rice 1% -- you see this is a bit of a rip-off because I'm paying for a lot of water). So if makes up the highest percentage of the ingredients, they may divide up names for corn so it's listed lower down and some meat product closer to the top, when in fact that's not the case.
So if you do your research, you'll find that you need to be independently wealthy so you can quit your job, go to a market every day, buy the highest quality lamb steaks, and spend your day grinding them and mixing them with supplements to create the only diet that is acceptable for any humane person to give their feline child.
http://kb.rspca.org.au/What-should-I...itten_267.html
(There's some other good links from a similar thread awhile back...)