You are very smart to ask for help here. Your relationship with your horse will be very different from any other. You need to learn how horses think and how to act around them to be safe.
Most of the respect you will gain with these horses will be gained by doing "ground work". Which is just that...working with them while you are on the ground vs. in the saddle. You should probably do 2-4 weeks of ground work before you even try to ride these guys. And for the riding part a trainer will be invaluable.
The others have given you some ideas about ground work but you can learn more by purchasing some videos. A small investment with a huge payoff. You will watch them over and over again. I can personally recommend ground work videos from Clinton Anderson, although there are several others too. I use his method and have been very impressed. You can get these on e-bay.
Check out the "natural horsemanship" forum. They will discuss a lot of ground work stuff there. Natural horsemanship is a training method that works towards developing a relationship with your horse, establishing you as the leader and thereby gaining their respect. Verses dominating the horse and whipping it into submission like people used to do. It would be best to find a trainer who practices natural horsemanship to get you started with this and the videos are a trainer in a box.
Clinton Anderson is one well-known natural horsemanship trainer and he has a club you can join for 20 bucks a month to connect with others, watch training videos, TV shows he's done, etc. I belong to the club and have for about 3-4 years. I love it. I don't mean to be selling Clinton Anderson to you but for me, his method has really worked. My horse is a dream, thanks to the techniques I have learned from him.
I just want to throw this in.
What to feed your horse: pasture grass or grass hay, all they want unless they get too fat, vitamins, salt block. (go easy on the pasture grass unless they are used to it). That's it. That is the best diet for a horse. If they need weight then you can feed a high fat feed like rice bran or low carb pelleted horse feed.
What NOT to feed: they should not get any type of grains. No sweet feed. They don't eat that stuff in the wild. They eat forage...grass and dried grass which is hay.
Good luck with your new horses. You will love it!