Hi and welcome.
It will be hard to identify your cat's breed without seeing, but as for other questions, a lot of experience here at pet talk.

Grooming is my specialty (as I am a pet groomer). A small size slicker brush is good to have around. But the best tool to keep the coat in tip top shape is a shedding COMB. This is a metal comb that has alternationg long and short teeth. And prevention is the best way to handle brushing. In other words, don't allow the coat to get matted. Knots grow into mats very quickly.

Iams is a good food, but the hairball remedy variety MAY cause diarrhea (as I found out) due to the laxative ingredient. You may wish to mix another variety with it. But if he hates it, you may just want to switch. I believe that all cats should eat dry food. Canned is OK for a treat, but I do not like them to become addicted to it. If you need to coax them to eat dry, mix the canned right into the dry (that is what I do for my 2 fussy eaters)

Feel free to ask more questions.