It sounds like you are doing your best to take excellent care of Ms. Sniffers. I have been raising and showing rabbits for over 30 years, and I can help with your questions. How much a rabbit will drink depends on a number of factors: whether or not they have been eating greens or other fresh produce, how much exercise they get, and the temperature among others. Do check to make sure the water bottle hasn't gotten clogged up and that the water is fresh. If everything is all right there, and Ms. Sniffles eats well is behaves normally, you don't need to worry about her water intake.
As for diet, the most important thing to feed is good-quality timothy hay. Don't use alfalfa because it can lead to health problems. Rabbits should be allowed to eat as much of this good grass hay as they want. You can usually buy it in a pet store in bags. If you can't find any locally, here is an online source.http://www.oxbowhay.com/index.sp
I can't emphasize enough the importance of feeding your rabbits hay. It will keep the digestive system working properly.
A five pound rabbit should also get about 1/8 cup of pellets daily.Use plain rabbit pellets, not any of the so-called gourmet mixes. They often contain seeds, nuts, and dried fruits which are very bad for rabbits. A variety of fresh produce, especially greens, is also important. Iceberg lettuce, however, isn't good. It has no nutrients in it and can lead to diarrhea. Spinach and kale are high in oxalic acid which can cause bladder stones. Onions and garlic are toxic in large enough amounts. Cruciferous vegetables, such as broccoli and cabbage are gas-producing, and that can also lead to digestive upset. The following link will take you to a site with detailed information on rabbit feeding, including lists of the best produce, and what foods to avoid:http://www.bio.miami.edu/hare/diet.html
Don't use cedar or pine chips or shavings for litter. Both contain oils that can irritate the skin and even damage internal organs. CareFresh is an excellent litter, and the aspen litters are also good.
You will need to clip your rabbit's nails. The first time, you may want to take them to a pet groomer or vet, and watch how it's done. You can get them used to having their feet and toes handled to make this job easier. Rabbits should not be bathed, but brushing is good for the coat.
I highly recommend this site for learning about rabbit care:http://www.bio.miami.edu/hare/rabbithealth.html
When you have some time, you may wan to go there and just read information in the various areas of the site.
If you have any more questions about this, just let me know by clicking on REPLY. I hope you will enjoy many years with Ms. Sniffers.