Thank you so much for the information!!
I went to the sticky you mentioned but haven't been able to go through all. I would definitely read through everything, and it's wonderful there are so much information. I have already learnt quite a bit, though I feel the need to know more and everything... BTW. which brand or varieties are your top choices. Rainbow is not a picky eater, although I think I have not fed him any healthy food but unflavered I suppose.
I bought some wellness and add some warm water to it, and I am thinking of making some homemade chicken broth for that. I wonder if there is a thing of drinking too much water?
Thanks again for all your time and advice!!