Great advice on getting your horse accustomed to dirt bikes. I was fortunate to have a nephew that rode dirt bikes come over with his and ride in the fields and around the round pen while the horses were in it. T, my mare, was accustomed to the sound and didn't faze her, and Walka took her cue and wasn't concerned, just curious. I then allowed Walka and T out into the field and Walka was very happy to "herd" the dirt bike. We have come upon dirt bikes on the trail and Walka is very calm and not worried because of his prior exposure. I do step off the trail, as our trails are very narrow, if we are not visible to the bike before it us upon us.
As far as the hunting issue, yes of course wear blaze orange, but you must also address the sound of the riffle being fired. We have accustomed Walka and our late mare T to this by target shooting often with various rifles. We are now in the process of desensitizing our new mare Misty to this. Unfortunately she has been kept in a bubble most of her life and is very reactive. Good thing is she looks to her handler or rider to decide what to do. There is nothing more unnerving then to be out riding and be taken by surprise by gunshots and have your horse freak out.
Be the kind of woman that when your feet hit the floor each morning the devil says, "Oh crap, she's up!".