Will a lion cut ruin my Persian cat's coat or change its color?

It's difficult to say whether or not the visit to the groomer could be related to his current clinical signs. Many animals can pick up a bug at the groomer due to the all the different animals going in and out of those areas. It can also be extremely stressful for animals, cats in particular. Stressed out animals have a lowed immune system, making them more susceptible to catching something. I would also do a very thorough check of him to make sure the groomer didn't accidentally cut him or cause him pain on any part of the body. Check the bottoms of the feet as well since you were mentioned them as an area the groomer was working on. From the picture, it also looks like Fella's tummy is really round, It could just be the angle or his weight, but this would be another area that might be worth looking at it if you decide to visit a vet about his current issue.

No, normally there should not be any noticeable change in a cat's hair coat regardless of whether she lives indoors or outdoors. Coat length and thickness are mainly determined by genetics, not the cat's living environment :)

It is impossible to tell from the pictures if this cat is single or double coated (especially in a white cat) - double coated cats have a short, soft coat underneath with longer guard hairs as an overcoat. It is very difficult to predict in kittens if this will be short, medium or long coated but the distinctive short nose and head structure of a pedigree persian does not appear to be developed here. The bald patch on the nose could be ringworm or also possibly a healing ulcer from herpes virus infection - both of these would be expected to grow back

Grooming long haired cats can be a difficult endeavor. I can understand your concerns about trimming all of the matted, or tangled, fur off of Cyrus, but these mats can be quite painful. If Cyrus' fur has become matted, it would be best to trim all mats. It is quite common for long haired cats to be groomed in a "lion cut" to avoid these mats. While their appearance isn't quite the same without the fluff, they can still be quite cute with a shorter haircut! Instead of using scissors, consider using electric clippers, as it is much less likely to damage or cut the skin accidentally. The lesion that you noticed on his skin appears to simply be a small, healing scab. If he has numerous scabs, conditions such as flea, environmental, or food allergies are more of a concern.

Yes, they will settle down and recognize each other shortly although it could take 2-3days

That spot on Lewis could be several things including allergies, skin mites, bacterial infection or ringworm (which humans can get). There are a couple things you can do at home and they can help but they may not address the underlying cause. You can try adding in an omega 3 fatty acid supplement for pets, this can help improve the skin health. You may also try changing his diet to something like Royal Canin or Nutro as they are aimed at skin health. Here is a link about ringworm: https://www.petcoach.co/article/ringworm-in-cats/ If the lesion does not start improving within a week or if it is getting worse, have him examined by the veterinarian. Testing for ringworm is easy and you may opt to do that whenever you like. I hope this helps and please feel free to post any additional questions.

Thanks for using Petco Pet Education Center, formerly Petcoach! This is most likely just saliva stain just meaning that he has been licking at it. It does not seem irritated so there is no need at this time to seek veterinary care. However, if at some point the skin underneath becomes irritated, bleeds or develops a discharge, have him evaluated by your veterinarian. Good luck!