Nice to see you getting some sound and sensible advice
I take a drink on all my rides, moreso when it's hot. For short rides like 15 to 20k, then I just have something like orange squash. When I'm riding further I sometimes use a zero calorie caffine drink (made by High 5) or I'll take 750mls of energy drink (I use Bike Food). As far as food is concerned, I might take a couple of energy bars, but I also take a couple of gels to give a quicker energy lift, a few people I know use honey rather than gels.
How much and how often is really down to how hard you are working, probably best to take too much and bring some home rather than run out of steam with 10k to go. If you are using a HRM, don't forget that digestion can put around 3 to 5 bpm on your heart rate.
BTW: I am very much NOT a pro, and this is just what I do as an mtb'er and newbie road rider.
"Try not to punch any clowns"