Anyone got words of wisdom?
I'd listen to Paul about bikes for off-roading, that's his passion. A hybrid or mountain bike is appropriate for dirt, and will work well enough on hard surface roads & sidewalks for short local errands. In fact, they handle potholes, curbs and uneven city sidewalks better than road bikes. Main drawbacks are the heavier weight, and the increased rolling resistance of the fatter knobby tires.
For longer road trips you want a bike with high-pressure narrow tires, dozens of gears, drop or triathlon handlebars, and light weight. But this won't work in dirt.
So you gotta compromise, likely go for a basic mountain bike to stay within your price range. You'll get a suspension front fork, but you can skip a suspended rear wheel, which adds cost, and weight that you don't need unless riding fast over very rough terrain. It'll have short, nearly straight across handlebars.
I would avoid a boardwalk cruiser or a comfort bike. These are heavier, slower bikes for neighborhood use, similar to the old classic pre-1960s Schwinns, a "paperboy" delivery bike. Some like the retro look & feel, with big metal fenders and fat tires, but it won't be good in the dirt, and will take more muscle to pedal it around than a modern style bike, and most are single speed.
Fit is critical, a subject for another post. Vital is "standover height" - where the frame top tube reaches your crotch when straddling the bike, both feet flat on the ground. And also seat height, with many riders sitting way too low.
My own bike is a touring model, a type I've been buying for 30 years, a heavier version of a road bike. Suitable for road use, it's also rugged enough for city streets, with slightly bigger tires and more rim spokes. It has 30 speeds, drop handlebars, and a factory rear rack on which I hang soft fabric panniers (saddlebags) when doing errand duty, and very light plastic fenders (always rain or watering puddles in Florida). For long trips I strip it down to the frame. Its factory production pic is in my public profile.