On the conditioning issue for a training level horse...I don't really worry about galloping schedules at that stage. Sure there are some fat drafty types out there who get tired at the end of a training level course and need more conditioning than everyday schooling and hacking provides, but most horses that are ridden for 45 minutes plus every day doing almost anything will be fit enough for a training level horse trials. 

But here's another perspective on galloping. Do it to school your horse and improve your riding. It's amazing how many hours we spend trotting and cantering 20 meter circles in a dressage saddle, and how few we spend learning to gallop correctly in open and hilly terrain. Most horses get strong and listen less when they gallop. They also express themselves on ways that we strive for in the dressage arena. I gallop to bring my horses' backs up, to teach them to push from behind, and to find that connected, in front of your leg feeling that makes you invincible on the cross-country course, and dynamic in the dressage. I lengthen and shorten, use half-halts to balance, do a lot of experimenting to see what works with each horse to settle them and keep their attention. I find it essential to explore with the horses that are going prelim or higher the wonderful world of speed. What do they do when you go beyond 500 mpm? Some take off like bandits until they realize it's all in a day's work. There is no substitute for practicing this stuff, and if your focus is your watch your less likely to focus on your schooling agenda.