First of all, I don't know why clavamox would be prescribed for anemia but if your cat has diarrhea and vomiting, ask your vet for another suitable antibiotic. I would also ask him why he prescribed an antibiotic.
With CRF it is important, I think, to figure out what stage of kidney failure your cat is at. Usually, when it is diagnosed, a cat's kidneys have already lost 75 % of its function. So regular monitoring and proper treatment are of the utmost importance in ensuring that the remaining 25% function as best as it can. I'm also interested in why your vet prescribed Epakitin so soon. Usually, a phosphorus binder is prescribed later in the disease - I can't recall exactly why but there are side effects to these phosphorus binders. There are others such as calcium carbonate or aluminum hydroxide, the latter of which is no longer used in humans. Again, I can't recall (damn my age) why but at the clinic where I work, it is used more than Epakitin. I think, from what I've read, there are pros and cons to both. I have never given calcium carbonate to a cat with CRF so I am not aware of its effectiveness or side effects.
I cannot emphasize more than the other posters about the importance of feeding canned food. It provides the moisture your cat needs, it is more digestible (which is important for CRF kitties as sometimes their tummies don't feel so good), and is generally better for cats. I know that a lot of people are dry feeders some for financial reasons and others just because they have always fed it and their cats are doing fine. However, with CRF, if you want your cat to live a quality life during the progression of this disease, then canned food is the key. i feed my 4.5 kg CRF cat 1.5 cans a day (half a can three times a day - again, smaller meals more often will not overtax his digestive system and thus, his kidneys). However, if financial reasons prohibit a full canned diet, then try to feed as much canned as possible.
It used to be thought that CRF cats needed a reduced protein diet but current research has pointed to reduced phosphorus as being key to prolonging the life of a CRF cat. Your vet will tell you that studies have shown that the rx kidney diets have proved to prolong a CRF cat's life as compared to a regular maintenance diet. I am not doubting it but as these diets are not as palatable, your cat may not eat them. So if your catis like mine, you'll have to find foods that may appeal to him but with a relatively low phosphorus content (<0.5-0.1 %). I feed Natural Balance's limited ingredient foods (all flavours), Wellness Turkey and Chicken (not the best choice but one he will eat in the middle of the rotation), Holistic Selects (Chicken and Lamb, Duck and Chicken? & Salmon & Shrimp), the occasional Almo Nature (not good for CRF but when he refuses all other foods, this has to do), and the occasional Hills k/d, Medi-cal Reduced Protein, Medi-cal Mature, and Hills g/d. Senior diets like the Mature and g/d can be fed to cats at the early stages of CRF. My cat usually refuses them but he will eat them on the rare occasion. I also give him 75 mls of subcutaneous fluids per day and the occasional famotidine (Pepcid AC) when his appetite wanes (meaning his tummy is not feeling well and thankfully, his appetite doesn't wane too often).
I don't know if your vet has a different approach to treating CRF - I am not saying what he is prescribing is wrong - who am I to say? There are different approaches. Some vets will prescribe Benazepril immediately after diagnosis. This is typically given to cats with heart issues but it is thought to help prolong the life of cats with CRF. however, studies have shown that this is true under certain conditions. One is the urine-protein-creatinine ratio (UPC ratio) which is basically a measure of the protein in the urine. It is also a measure of the damage to the kidneys and blood pressure and something called secondary parathyroidism. I don't understand this enough to explain it but it has to do something with calcium, vitamin D and its progression results in bone density loss and other things. Calcitriol is often prescribed either immediately or at a certain point of CRF - many approaches to this as well. If the UPC ratio was >0.1, then CRF cats given benazepril had a longer survival time. UPC ratios <0.1 did not show any significant difference between cats given benazepril and those not given benazepril. At my clinic, (again, not saying this is the right and only way, just one approach) they prescribe benazepril when the UPC ratio is <0.4. that is the dangerous level for cats (for dogs it's 0.5 and over). So once the UPC ratio is >0.4, the cat is at risk. So I would suggest having your cat's UPC ratio monitored regularly. Some vets believe that benazepril can reduce the survival time of a CRF cat or at the very least, increase the clinical signs of CRF so these vets probably only prescribe it when the UPC >0.4.
Also, a urinalysis and a culture and sensitivity should be done regularly as well. If the kidneys are filtering and concentrating urine properly, then the urinary tract is protected from infection. However, if the kidneys are not concentrating urine properly, then the urinary tract is not protected from infection. Doing the urinalysis and culture will determine if there is an infection - they will also determine the urine's specific gravity which determines how the urine is concentrating. Usually, it's low in CRF cats so the kidneys are basically retaining the toxins as opposed to excreting them into the urine. Regular urinalyses and cultures will detect infection which can be treated so no further damage can be done to the urinary tract.
Usually, an xray and/or ultrasound is done to see the size of the kidneys (i.e. the amount of damage done - if they are smaller than normal, that means damage has been done) and the texture of the kidneys.
Regular bloodwork, urinalysis cultures and UPC ratios to monitor your cat's CRF are usually done every three months, longer if his values are stable. My cat's values are now stable and have actually reduced somewhat (knock on wood).
There are many supplements out there that purport to support the kidneys. A popular one is Azodyl. it is a probiotic which purports to reduce the BUN (blood urea nitrogen) and creatinine going through the kidneys. As these are both markers on the bloodwork on which vets base the progression of CRF, this on the surface sounds like a good idea. However, BUN and creatinine are not the only factors that are involved in kidney disease so you may be given false hope. I used to give it to my cat but stopped it as I didn't want to give a huge pill for nothing. I have read and spoke to many vets about Azodyl and all of them said that it doesn't make much of a difference. Just giving that example to be aware. As CRF progresses, you will have to give more meds so why stress your cat out for nothing?
I know this is a lot to digest and I'm sorry if I have confused and overwhelmed you. That is not my intent. My intent was to further inform you so that you can make sure your cat gets the best care you can give him. The more knowledge you have, the better your cat will be. IMHO, I would get a second opinion. I'm sorry about your cat's diagnosis, but she can live a quality life if treated properly and conscientiously. Vibes to you and your cat...