Hi. Please go easy with the Tramadol, as that can cause a deterioration of the kidney disease. Only give when really needed. The antibiotics will also likely cause stress on the kidney function, so I wouldn't necessarily anticipate any improvements to bloodwork until the course(s) have finished.
I'm delighted you are giving SubQs at home. This is really maintenance after IVs, to help support the good work the IVs have achieved. SubQs should be done DAILY, which I hope are being done. Also, the dose needs to be accurate - can you let me have your dog's weight and current creatinine level, so I can check that for you.
Has your vet checked his blood pressure? If not, that needs doing. Further details in my article below (follow the link), which I am sure you will find helpful.
http://www.infobarrel.com/My_10-Point_Plan_for_Dogs_with_Kidney_Failure
I think it is best for you to keep to the canned kd food for now, rather than start homecooking. There will be a time when you need to homecook, as almost all kd dogs go off their food at some stage and it can be an uphill struggle to get them to eat at that time. The kd canned food hopefully will give you plenty of time to research homecooking more fully so you can be adequately prepared. In the meantime, there are a couple of my articles on diet which I would like you to read please ...
http://www.infobarrel.com/How_Diet_Affects_Dogs_with_Chronic_Kidney_Disease
http://www.infobarrel.com/Changing_Diet_During_Canine_Kidney_Disease
In terms of useful supplements, I would start now giving pure organic salmon oil together with a canine formulated Vitamin E capsule. This provides omega-3 fatty-acid, which is a very good anti-inflammatory to help support kidney function.
I wouldn't worry too much about him not drinking water. Not all dogs are good drinkers. The canned food will help, as it contains about 80% water, so will help flush the toxins from his system and keep him hydrated. Always have fresh water down for him, and if possible use filtered water as it contains less sodium. You could also give a chicken broth if you feel he needs more hydration (just cook up human-grade chicken with some veg, like green beans, and pass it through a sieve for him to lap at. This is both nutritious and hydrating.
If possible, feed much smaller meals more often. Six meals 2 hrs apart or four meals 3hrs apart help relieve the stress on the kidneys, as they don't have to work as hard removing the by-products of eating.
Kind regards
Tony