Lots of questions to be answered please?

I have a very nice looking Beagle male that is 6 years old. I just purchased him for competition from a very well known kennel but he isn't working out well. I have him with a very good trainer and he has tons of bad habits that the trainer feels will stick due to his age so he is coming back home. He has run AKC SPO southern and UKC Performance Pack and is always picked up. He swings, leaves the check area too soon and is looping in front. I am not a field person, so I guess this means he runs past the dogs on the line to get where he thinks the rabbit is, leaves the trail too soon after losing the scent and tries to find a new one and runs a trail up front, loses it and then loops back around to find it again. I am very disheartened and you would choke if I told you how much I paid for this 6 year old boy. The up side is he is very well put together with tons of head and could have finished an AKC show Championship if I would have gotten him at an early age. Now that he is older he is not only gray but really tattered from running with patches gone on his tail, chunks out of his ears and scars and so on. He also never runs off game and is very very gentle with all dogs and pups, kids, loves attention and listens well no matter where we are. He is also a very willing and talented breeder and easy keeper. To me he is still valuable to me as a breeding dog and so I am still hopeful that we will get something really nice out of him. So here are my questions -

1) I understand that the bad habits he has may be genetic but when a dog swings, loops and gives up are they most often learned issues or genetic traits?

2) Before screwing up my breeding program is there a way to tell if his pups will have these issues and at what age will it start showing?

3) Some people have suggested running him alone to see if he will get better. I think that is a good idea but really, how much could this help at this age?

4) I will never run him with any dogs that are not very experienced as I do not want younger pups learning anything he has to teach but will running him with other experienced dogs
also be a bad idea?

On another subject or two here are more questions please -

1) I have nothing that runs besides the dog above and lots of pups to start. I am sending them off with a wonderful trainer but I always will have a few here between rotation.
Should I purchase a reliable old bitch or dog that is solid, slow and has no bad habits to keep my pups started and help them with confidence or to get them out and about hunting?

2) If so... any other words on this you can share? I know this has quite a bit to do with trusting the person that is selling the old dog to you and I don't want to get another that is
simply not safe to run with younger pups so I will be sure to send this old dog to my handler just to evaluate and give the blessing before doing it but anything else you can tell me is
greatly appreciated.

3) Have you found that pups that really love food will hunt hard when they realize they can eat a rabbit or are there any traits as a young pup that seem to go along with being a
solid hunter with desire or does it seem very random who turns out to be superior hunters and no way to really know for sure which pups to keep initially. I really do not want to keep
an entire litter but I will if there is no way to tell for sure.

4) Any words of advice for a fairly new person who's goal is a true dual AKC Champion?