IRN are indeed very "wild" birds, so if you're looking for a cuddle bug I couldn't say I recommend them. It's not to say they won't tolerate touch, but they're well known for their hands-off mentality. They also take a lot of stimulation as they're incredibly intelligent... Shiko is my 3 month old IRN, and he immediately picks up any training we give him, so he needs constant stimulation and he also needs his cage reorganized to keep him entertained

He's incredibly cute when he plays, and he'll grab a foot toy and hop around... it's so cute!
So, from my experience, IRNs are great birds for training due to their high food motivation and intelligence, but they take a lot of work and require lots and lots of attention to stay... "willing", for a lack of a better term. Of course, you'll never know until you have the bird. You also get a double dose of hormonal behaviour, as they bluff at a young age. Thankfully Shiko doesn't bite, but they are known to get incredibly aggressive for up to a month or longer during this experience, and during that time you must remain continually positive. And, for whatever reason, a lot of owners say you should take the bite from them through this stage. Shiko simply lunges and knocks you with his beak, but not all ring necks are so forgiving and gentle.
He's also VERY destructive, and I have to buy him new toys constantly because of it. He has to be chewing on something, so he's a poor shoulder bird, haha. That can be trained with stationing, though, but I can't imagine he'd sit long even after being fully trained. We do station training with him, but after about 5 minutes he couldn't care less and wants to hop along and play with his toys, haha! IRNs are excellent talkers, but Amazons have a clarity like no other and are known to mimic extraordinarily well. IRNs sound more like a child on helium when they speak, haha.
Any bird can be trained to not leave while going outside, but I can't say I'd recommend ever taking a bird out without being restrained, unless you've trained them for years for it with the proper restraints. You have to remember that they're prey animals, and are keen to quickly fly away should they feel threatened, even if they're well trained.