Hi my name is Josh, I've worked in the horse dept for 5 years hopefully 6 this summer. 2 of those summers I worked as a cavalcade horseman which is the person who is in charge of the cavalcade as far as teaching horsemanship leading the rides and making sure that you get some camping experience. I'll give you as much advice as possible.
First I'd like to tell you that the horseman and wrangler who leads you on your trek are not rangers. We don't go through the formal training a ranger does as far as the camping side is related. We get one half of a day to train with to learn what a ranger knows, where rangers get about 2 weeks of constant training. Also this means that we don't sleep with the crew, or eat with a crew sometimes. This may seem rude at first but understand that we are there for your saftey around the horses and to take care of the horses as well as make your trek enjoyable so we sleep near the horses in feed shacks. Also horseman are actually on the trail for all but about 12-14 days of the summer where the rangers actually are on the trail only about half the summer because of days off and picking up crews. This makes the horseman tire of trail food incredibly quickly as you might imagine. Cavalcade horseman call this the cavalcade diet, I personlly lost ten pounds each summer and I only weigh 155, I dont have a whole lot to lose. So the horseman tend to eat with the staff in the camps instead of with crews.
More towards the training point of your question. The crew needs to whitle down what they need to take dramatically from the past treks. This is a major sticking point many crews have. The duffle bag you should have received in the mail should be able to fit a sleeping bag and your changes of clothing, and possibly as well your hiking shoes. I know this seems impossible but trust me I did it for 2 summers. The changes of clothing should consist of 1 pair of pants and shorts, 2 pairs of socks, 1 or 2 pairs of underwear and a t-shirt and long sleeve shirt as well as a pair of sleep clothes that never even come near the food (which you probably know). That is actually more than I ever took on a calvalcade for clothes, generally I took a pair of pants, long sleeve shirt, one pair of socks and underwear. Remember this is high adventure and everybody on the trail smells just as bad as you do and if they don't they've had way too many showers. The reason for the single duffle bag is to keep the weight down on the pack horses. Too much weight causes way to much stress on their backs as well as causing them to get saddle soars which make them unusable for many weeks. You'll also get a set of saddle bags each to carry your food kit, your journals, your wash kit and so on. The saddle bags aren't real big, only about 8 inches deep and 6 inches wide and an opening of about 2 and 1/2 inches. But there are two pockets that size. Oh and please dont forget the 2 collapsable water jugs, they are important.
The crew should not expect to get to run the horses until the end of the trek, it is incredibly dangerous on the trail and roads we use. They will however compete in a gymkana which means games on horseback and should be described in the manual. As far as training with the horses go, any you can get is good and makes the boys more comfortable around the horses.
However Phimont will do another training for the crew, teaching you the Philmont way of doing things. We do it because in our experience the way we do things is the safest way. The one thing I can say is spend as much time in the saddle before Phimont as possible to alleviate the chance of becoming sore during your rides, this will let you enjoy Phimont and the rides more. Oh and one more thing about the rides you'll be taking at Phimont, you will be in a single file line the entire way, breaking line with the horses will cause some of the horses to kick and you could get hit, possibly getting injured. Also depending on your horseman the might be willing to do the horsemanship merit badge with the boys. Not all horseman do this but if you ask they most likely will be willing. As you know Philmont isn't a merit badge camp, so its not required. I did the merit badge with the scouts but some dont.
I've probably talked long enough but if you have any specific questions I'd be more than willing to help. I hoped I helped but realize I couldnt answer all your questions so if you have anymore please feel free to e-mail me. Oh and one last thing, I am not going to be a cavalcade horseman this summer but if you enjoy the trip the horseman appreciate tips, not necesarilly monetary either. Dinner afterwards or a crew t-shirt are good. Your horseman and wrangler won't ever ask for anything and this being Philmont you'll never hear anything about it sometimes you dont think about it. But all of that is dependant on you enjoying your trek, dont tip them if they don't make your trek enjoyable, because then in my eyes we aren't fulfiling part of your Philmont experience.
Again please mail me with your questions, oh and by the way sorry about the spelling and grammer errors, this program wont allow you to go back and edit, I'm on my schools computer system right now sorry.
Philmont Horse Dept 94-98 maybe 99