Best food an opportunity for your cat?

So I lost 2 cats to kidney failure pretty close to each other, a half year later we adopted 2 new teenage brethren( 6 months old ).

Because of our last 2 cats we wanted to be more strict on their diet and make sure they are getting the best of the best to do our best to prevent illness like this. We fed our old cats things like imagination feast and friskies, things like that and would switch out between hard and wet food.

I’ve been doing a TON of research and I want some assist, advice, or answers because I hear a ton of different opinions. I’ll try to make this as short as possible.

One thing I’m SURE of is that I want my cats to be on a grain free diet. This attains the most sense to me because cats don’t have grains or complex carbs in their( natural) diet. I get it. This I have no issue with, and this is where it gets complicated…

Hard food and wet food? I have my vet telling me to feed a mix of both with emphasis on wet food.( Wet food to get that moisture to your cats as they are desert animals, dry food to put some wear on your cats teeth so they don’t rot and have some sort of cleaning on them ). Then I have Tons of articles telling me that dry food is the devil and doesn’t do any actual teeth cleaning and to just brush your cats teeth( if they’ll even let you! I swear every cat blogger has a saint cat ). What are other people’s thoughts and opinions on this?

Guar gum, Xanthan gum, and Carrageenan? Seriously I see tons of articles claiming this stuff to be the worst, but no actual scientific proof to back up their asserts besides( well this article here said that maybe sometimes they maybe sorta could cause cancer ), but I frankly can’t tell if it’s legit science or “OMG GMO’S WILL KILL YOU” mumbo jumbo … I strongly believe in science and I am not worried about GMO’s and I don’t think everything you touch that isn’t 100% all natural will give you cancer. So what’s the actual deal with this? Is it ACTUALLY harmful to my cats, or is it only “vaccines cause autism” syndrome?

Is fish truly that awful for my cat? Plenties of cat blogs say that fish is terrible for my cat, I only give it to them a few times a week because of this. Is it really that bad for my cat?

Raw food diet? I don’t know how good this is for my pets, it seems to construct the most sense, but it seems like a lot of work and hour that I severely only don’t have and it’s wayyyy too expensive to buy the “premade” stuff.

Taking all this into account. WHERE can I find the stuff that fits all this criteria without spending the thousands of dollars that they also like!( They hate pate’s and merely like the stuff with gravies and chunks/ shreds) I’ve been feeding them a mixture of mostly wet food( weruva variety, tikicat) and blue wilderness adult grain free cat food with feline natural chicken and lamb freeze dried cat food sprinkled on top( to entice them to eat it) but it’s literally breaking the bank I’m spending almost 200$ a month for the two of them and it’s sooo expensive. Anyone have any alternatives or anything they can give me tips-off on to save some money without sacrificing my cats health, my period, and my sanity?