You might consider an "architectural" steel door and jamb unit. Not sure what the market offers, but there are products out there (just bring $).
Stay away from Home Depot and hardware stores for quality locks - they simply are not sold there. Go to a standalone locksmith for recommendations.
If you use conventional exterior doors, consider that the hinges are the next "mechanical fuse" after your heavy-duty deadbolt lock and reinforced strike. The hinges themselves are usually OK, but they are commonly mounted on both door and jamb side with screws that are not very robust. Especially on the jamb side, you want screws that will go beyond the first framing member and well into the second. If you've ever seen a door kicked in, almost always the hinges remain attached to the door but are ripped from the jamb.