Depends on what you're doing with them. Only horses at the very high end of the exercise/performance spectrum or horses that are stalled extensively need 3X a day, IMO. My horses get fed when I call them in and catch them. They are in light work and on very rich pasture.
2) *ONLY ANSWER THIS QUESTION IF YOU CARE FOR YOUR HORSE AT YOUR HOME* Is it difficult to care for your horse and maintain good grades in school all at once? Again, my horses are low maintenence. When I was in school, boys, music and parties interfered with my grades way more than the horses. Also, the job I had to support the horses interfered way more than the horses.
3) Does owning and caring for a horse help you stay in shape? Yes. What others said.
4) Do you ever regret purchasing your horse? Was it a BIG change? Never, ever, ever. As necessary as breathing.
5) How often do you ride your horse(s)? No where near enough! 2 - 3 X a week for right now.