Welcome to the serious corner! Look in at the Behavior forum, as well. The Health and Nutrition and Behavior have both added tremendously to my understanding of my cats, and also to what is normal and not really normal -- a very important subject, since "normal" for cats varies every bit as much as it does for humans.
I have a reasonably steady 14-18 cat population and (at present) 5 dogs -- all rescued from the street and all spayed or neutered so we don't increase except by rescue. Most of my cats are young -- 1 to 3plus years old, but I have one cat (Gypsy) who is now 12 years old.
I assume your cat is neutered. If not, discuss the health benefits with your vet. Also discuss such things as increased urinary and digestive problems. A pity about the teeth. I have one cat (Little Black, now almost 4 years old and an enormous black panther of a male) who is prone to poor teeth, and at 3 and a half, I had to have his teeth cleaned (they must do this under light anesthesia) because they were so discolored I was afraid they were rotting. So far, he is the only one with this problem. If you ever have a young cat with dental problems, it is best to get on it as early as possible -- you might be able to keep her/his gums and teeth healthy into old age. I assume that, in conjunction with, perhaps, a genetic tendency, as in humans, the severe malnutrition Little Black survived until he managed to find me at about 2 months was the reason for his chronic teeth problems. He got his name because he remained almost 3 month-sized until he was more than a year old.
My cats are given the run of the house, and often sleep inside -- the day cats at night and the night cats during the day -- and during the winter ALL the cats almost around the clock. It is always a real gas to watch the spring and summer kittens reacting to the first winter rains (hopefully no later than November). We have a lot of thunder and lightening -- big desert storms, only rain instead of sand -- and that on top of getting pelted from the sky with water sends them hiding under bushes or running for the safety of their nesting places in the house. I always wash my cats once or twice a year, so none of them is particularly afraid of water or soap as such, which is useful if they get some kind of toxin on their feet or coat. Which is not to the point of your question.
The cats also have the outdoors. I have a relatively dog-proof fence around about a half to two-thirds of an acre of garden, but it is not cat-proof. I hope to build a cat-proof fence and gates this winter, since I always lose several cats a year to deliberate or inadvertant (agricultural pesticides and vermin control poisons) poisoning, cars, and cat-killing dogs. My vets estimate about 80 percent of all outdoor, stray or feral cats will die from one of these causes, so I am doing pretty well with less than one-third of the attached cats I consider "in-house" -- I can't speak for the ones who just drop in for food or for shelter in the store house, or the ones who stayed a year or two and then went feral again -- around 20 cats over the past 3 years. However, even in my yard, there is scope for hunting (particularly where the compost piles are maturing), tree-climbing (there are 8 very suitable trees (cedar, pine, olive, mulberry) of proper size and 3 smaller trees that don't offer any challenges yet), and grassy or bushy areas for sleeping or sunning in good weather. Being outdoors and able to exercise helps to keep their muscle tone and their hearts healthy. I also give them an old sofa off the side porch to sleep on, altho the dogs usually monopolize this spot, as they do my bed (the only one in the house) when I am not in it. In the house, however, it is mixed company, and cats and dogs of all ages sleep in big tangles -- up to all five dogs and 6 or 7 cats at a time in the winter, and it's a single bed!
So my cats are both indoor and outdoor, which makes it harder to keep them safe, but which I think enhances their overall mental and physical health while they are with me.
My vets tell me that soon I will have to switch Gypsy to "elder-cat" food. They say that the balance of calories, vitamins, and, particularly, minerals is different for the 4 life stages (neweborn to 2 months, kitten & growing, adult, elder) (not to mention special food when a cat is sick). Within the limits of my budget, I try to accomodate. I have one younger cat (almost 3 years old) whose bladder develops stones (this is usually an older cat problem), and he is on special low-magnesium food. Fortunately the crystal formations were dealt with chemically, and so far we haven't had the problem of an operation -- and also fortunately, there has been no further evidence of crystals for the past 6 months. I occasionally mix in elder food for my oldest cat, and I notice that the kibbles are smaller and more easily crushed than the regular cat foods.
As to temperament, Gypsy has a history of extreme jealousy and bad-tempered paranoia, but yes, she is beginning to mellow and return to her early behavior patterns of affection and desire to be loved. She is still capable of quite vicious and unexpected attack on the other hand (and it is usually on the other hand than the one I am trying to pet her with!), and does not permit any violation from cats or dogs of her "special" places or food dish. Every newcomer (and including myself and guests) learns very quickly to never bump up against her, even accidently.
I know there are all kinds of people on this site who will have much to say about their older cats. You are asking the right questions at an early age. I ignorantly mistreated my own occasional cats for the first 60 years of my life, and I wish beyond most things that there had been such a wonderful source of information from so many real cat-loving people. You are blessed to be born in the internet age, and your cats over the years will be twice-blessed -- that there are such forums and that you care enough about your furball friends to share your experience and ask questions.