2 Betta's In Need of a Diagnosis

Are the white spots simply water stains in your first photo or actually on him?

As for him not eating, sometimes that happens if the light is out for a while and your betta falls asleep. When you turn on a bright light suddenly, they wake up and swim around but they don't respond to things. I'm not certain, but it's almost as if they're sleep swimming or their eyes have difficulty adjusting to the sudden change- sort of like when your eyes are used to the dark and then you turn on a light while looking at it. I've accidently done this to my fish a few times and tried to feed them, but they ignore it (they're fine in the morning though)

The second boy with the red spot on his ventral fin looks super healthy actually, and it could just be a coloration of his fins

But just to be safe, could you try and answer all of these?

Housing
What size is your tank?
What temperature is your tank?
Does your tank have a filter?
Does your tank have an air stone or other type of aeration?
Is your tank heated?
What tank mates does your betta fish live with?

Food
What type of food do you feed your betta fish?
How often do you feed your betta fish?

Maintenance
How often do you perform a water change?
What percentage of the water do you change when you perform a water change?
What type of additives do you add to the water when you perform a water change?

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Ammonia:
Nitrite:
Nitrate:
pH:
Hardness:
Alkalinity:

Symptoms and Treatment
How has your betta fish's appearance changed?
How has your betta fish's behavior changed?
When did you start noticing the symptoms?
Have you started treating your fish? If so, how?
Does your fish have any history of being ill?
How old is your fish (approximately)?

Nice looking boys you have...

The first guy looks to be he had rubbed hard against a rock, hard decoration or a rough substrate and knocked off some scales- they don't look infected, and will grow back. It doesn't look like fungus, fungus you would see white cottony growths with fine hairs sticking out, that's just smooth skin.

You can keep him in the AQ salt (1 tsp per gallon, pre-dissolved, daily 100% water changes adding in mixture of salt each time for no more then 10 days) to make sure no bacteria builds up on it. -- After seeing you normally place AQ salt into the tank, I don't think this is needed, but if the spots turn red as if being irritated/infected then this is the treatment needed.

After that just keep up on the weekly water changes (which I will address at the end).

For the next guy, it looks as if the rot has cleared up and I can see the new growth on all of his fins- a good sign (the clear edging). Keep an eye on it just in case, but I believe it should clear up if it is remnants of the rot- otherwise it could be a new color he has developed (normal for bettas to change/add coloration).
The rot wouldn't be cleared up in all other areas, and start in a new one while under treatment. So I wouldn't worry too much about it unless you see it get worse.

The nutrition seems like a good variety of good brand ones- Make sure not to overfeed, the pictures could be right after feeding if not then I would make sure that you are only feeding 2-3 pellets per meal/2-3 blood worms and a tiny pinch of flakes per meal twice a day (if mixing per meal, or if mixing 2 in one feeding, make sure to not pass 3 total whether it's pellets or FD).

You say you only add in a tiny bit of AQ salt during water changes, but nothing else:

You will need to pick up some water conditioner (there is a list of them on a link in my sig), and stop use of AQ salt: unless it is being used for treatment purposes only, and for only specific treatments, and for specific amounts of time.
Overuse, over exposure of AQ salt can harm the kidney/liver functions and can cause failure. It can also cause bacteria and viruses that the salt normally would kill to become resistant to the salt, therefor the salt won't work the way it should.
AQ salt is not recommended for long term use on bettas, and highly recommended you not- there is not enough good benefits of using salt to outweigh the danger of using it with them.

In tanks of your size, unfiltered, 1 change a week at 90% is no where near enough to keep the water clean and in the long run, keep your fish healthy and living a full life span. For those size tanks you will want to be doing 1 50% (water only, dosing the tank for the full volume of water conditioner) and 1 100% water change per week with only water conditioner. Ammonia among other things can and do build up quickly in tanks those sizes and without the needed 100%s, the salt you are adding in is building up slowly to dangerous levels over time (why the daily 100% is needed when using a salt).
Water can be too clean, just as it can be too dirty.. it's a calculated thing that depends on where you get your water (I am assuming tap water for you), live plants, filtered, cycled, etc.
But for everything unfiltered, under 5 gallons, no live plants the recommendation is what I stated above at 1 50% and 1 100% per week.
The only 90% per week can cause your first guy there to become infected on his wounds, which is not something anyone wants. And for the fin rot to develop on either of them the next time they get any type of fin damage.

Good luck with everything, you are doing a great job, just need a tweak