what should I eat and drink before a race?

Given its a 10K, then you do not have to worry about taking energy on board via food/gels etc. You have more than enough already stored in you to last you through that distance, plus it can sometimes stick in your stomach uncomfortably if you have not already tried and tested to see which ones suit you. Anyway, the way to think of it is that energy food/drink is for endurance races.
For any running/racing, always make sure you are hydrated. There are loads of suggestions on the web about how much you should take on daily, before, after runs etc but they are only general guidelines. You need to work it out for yourself, for example, I sweat a lot (A LOT) and take on a lot of water while running and end up mostly well hydrated. But for general advice, you should be able to pee mostly clear, the darker the pee the more dehydrated you are. See what works for you. That being said, drink first thing in the morning, as much as you are comfortable with, drink about half hour before race too. I find that when runnign a 10K, it is done at a relatively fast pace and you should find there will be at least 1 and probably 2 water stations and I think that 2 water stops is enough for 10 k during the race.
As for eating the day before and the morning,....eat as normal the day before and as normal in the morning, whatever normal is. Again, I would say that there is less need to eat for endurance energy (ie carb loading) as you are not runnign an endurance race. The most important thing then is to eat somethign that will clear your system before the race, and you wont feel bloated or uncomfortable during it. for me its porridge about 3 hours before the race. No need for anything special the night before, in fact maybe a lighter dinner than normal as a 10k is a distance you dont have to worry about endurance and you want to be as light on your feet as possible :)
Best of ;uck