Welcome to the forum, Molly. Glad to see you getting back into more bicycling. Good for you.
The first thing you need to know about riding gravel is that there is no standard as to what constitutes a gravel road. Gravel roads can be anything from hard dirt with no gravel to hard packed, small gravel (best for riding) to deep, loose gravel (really tough unless you have a fat bike or a plus tire bike). Also, gravel roads can be relatively smooth and flat (best for riding) to washboard and rutted (tough for riding). Then, to make the issue even more iffy is how well and how often a gravel road is maintained. A fresh new layer of gravel can really slow you down. Weather is another factor. A rain often tends to firm up loose gravel and make things easier to ride. A heavy rain, though, can create potholes and so on.
DON'T let me scare you off, though. I love riding gravel. It takes me places that rarely see a bicyclist. It takes me places I can't get to on pavement. It will open up HUNDREDS of miles of riding for you in a place like Kansas or the other prairie states. It really is adventure riding at it's best. I love it.
On a good gravel road with the right bike, I can maintain a good steady 10 mph, no problem, and even higher if I really gun it. On our roughest gravel roads, which turn to sand, up here, it's more like riding a mountain bike on a trail. Then I'm down to half that speed.
Riding gravel is part art and part technique. Unless you are riding a fat bike, which allows you to just plow straight ahead though anything, you need to learn to pick a line ahead of you as you ride, judging the best way though the gravel, often changing lines to accommodate changes in the gravel. On some stretches, i find it's easier going along the very edge of the road - less gravel and fewer ruts. In other sections, I find it easier to ride on the crest of the road in the center. Turns in the road call for extra caution. Those are often places the gravels piles up. Navigating it all comes with experience, but it becomes second nature after a time. One thing for sure, it's always interesting. The way you rode the same gravel road last week, may not be the best this week, due to the ever changing conditions on gravel roads. Guess that's why I love riding gravel so much.
You'll want wider, more all purpose tires than on a standard road bike designed for pavement. 700x35s are even a bit wider are the norm for drop bar gravel bikes. You want some tread, but not too much tread or you lose rolling speed. My favorite gravel tires will have mild, easy rolling tread in the center, with some higher lugs on the side for cutting though the deep stuff and controlling fish tailing. The tires you have on your hybrid are probably your best bet for now. They tend to run wider than standard road bikes.
I've never had any issues with gravel hitting me in the face while I ride. I wear glasses, full time and have never nicked my glasses while riding. The one situation that can get you sprayed with gravel is a passing car, but if you're on a gravel road with heavy vehicle traffic, that's not a good place to ride.
DO use a blinkie - a red flashing light - no matter what time of day you ride. On a day when dust gets kicked up, easily, you want to be seen by passing cars. Then, too, a lot of drivers don't expect to encounter someone on a bike while driving on a gravel road. A blinkie lets them know you're there. Carry all your basic tools and an inner tube, plenty of water, and in a place like Kansas where you'll be way out in the middle nowhere, a cell phone.
Anyway, please do let us know how it goes. Ask away with the questions.