As for training your birds, I'm going to paste an explanation I sent to a guy who I gave some squeakers to for him to start a loft. I hope it helps!
Below is some explanation of how you can settle and train your young birds in two main training stages.
As I mentioned, you really have to build an aviary. With young birds not born in your loft, you already sort of have the odds stacked against you in terms of losses, so you want everything going in your favor. You'll also want to build a settling cage and landing platform, which is simply a removable cage that you can place over the bob door. It is extremely difficult to train young birds with out them.
First step, settle the birds. I would plan on a 2-3 week settling period, where you do not let them out. This is a time for them to get used to the loft, and download images of the surroundings by viewing from the aviary and settling cage. Ideally, your bob door and settling cage will sit just above your aviary, thereby making the top of the aviary your landing board, but it's not a big deal if you can't build it like that, it just makes it easier if it is. Once you notice your birds freely entering the aviary on their own to look around at their surroundings, I'd let them continue to do that for about a week. At each interval of this training process, your birds are memorizing what they are looking at, literally "downloading" images into their photographic memory of what "home" is. Next, train them to use whatever door (be it a bob door or open door) you want them to be able to enter in and out of the loft with by using a settling cage over it (i.e., the cage covers the outside so they are able to go in and out of the door, but they won't escape because the settling cage blocks them). Do this for another week. (If you use one-way bobs, at first keep the bob wires all the way up, then after a few days drop just one bob wire, get them used to that (it gets them used to touching the metal as they go in and out), then drop a few more bob wires, until you get them to the point where you can drop all of them, at which point you'll actually have to place them into the settling cage from outside since they can't get in with all bob wires down--at this point, they will be forced to use the full bob door in order to get back in the loft. That's also the reason you want to build a small door on the outside of your settling cage.) Make sure you have evidence that all of them understand how to exit and re-enter, and also have evidence that each youngster has spent some time in the settling cage. If just one bird isn't confident using the bobs, that could keep that bird outside in the future, and may be lost. If you notice some aren't going in there, you might step in and put them in yourself, forcing them to learn to re-enter the loft through the bobs.
Second, first freedom. Next, you should let them out by simply opening the door. This is very important. With birds born in your loft, you should be at this stage early enough that they aren't strong on the wing enough just to take off, but since you got young birds elsewhere, you need to be careful since they WILL be strong on the wing. I recommend soaping their wings the first 2-3 times you give them freedom (see YouTube vids of it, just a light soap and water solution in a 5 gal bucket, dunk their wings for 20-30 seconds until soaked). Because you have to do this, you can choose whether you soap the wings and place them back in side and let them exit on their own time, or you can simply place them on the landing board yourself, right after you're done soaping their wings. With wet, soapy wings, stead of being able to fly, they should just flutter about. They likely won't have the confidence to just take off yet, but if they did there is a good chance they'll fly too far and not come back. They will likely stay on your landing board (you should have a landing board attached to your loft entry), or at most hang on the roof of your loft. This is good, because they continue to download images of home, as well as get bearings of where the door is when they flutter about their surroundings. After a few days you'll notice they might go a bit further, such as the telephone wires or maybe the roof of your home if it's close to your loft (but sometimes they may stick around for a week or so, just be patient, it's different for each bird). Keep letting them out (evening, with 2-3 hours of light left of the day is best) each evening until you start noticing they gain confidence to fly around fast around your loft. Then experiment with giving them more like 4-6 hours of time out there. You know you're ready for basic training to be over once you notice that they disappear out of sight for more than 30 minutes or so, and still come back to home, at which point you can be pretty sure they have become dialed in and are ready to be true homers. This is because they have flown up high and literally downloaded images of everything, for miles, or at least should have. At this point, if you want to, they should be ready to be trained on tosses at 1 mile, 2 miles, 5 miles, 10, 20 and so on. For safe measures, you might loft fly them a few more times, but in theory, after one trip of disappearing for some time, they should be ready for tosses. If loft flying is all you want to do, you can just keep doing that with them. If you want to train them on tosses and use them in traps for dog training remotely, away from home, make sure at each mile interval you do a few tosses as a group, and then also release them in singles a few minutes apart from each other, so they have individual confidence flying alone, because when you use them in the dog training traps, they will be released individually, so they should be ready for it.
So, basically it is this:
(1) settle to aviary and settling cage
(2) train to use bob doors
(3) train to sit on landing board and observe, without being strong on wing
(4) train to loft fly strong on wing
(5) train remote tosses
Even with what I've said above, even if you do it all right, you might still have some losses. It happens. My experience also is that losses are greater if you get the birds from another loft and they aren't born in your loft, even if you get them at the right age where they still have the yellow fuzzy down feathers on them. But the above steps should greatly mitigate losses. I would avoid flying much past September, unless it is in your yard and you have them trained to trap back quickly, as hawks get bad, and stay bad through winter. End your year with at least 4 or so so you can have babies in the spring and really get things going.