Well he sounds like a typical 5 month old to me but he also seems like he's making a fool out of you. If you have to repeat a command over and over again then you have a problem but he's still real young to expect him to know and follow commands. Training takes years and just when you think they have it they show there ugly side again, lol, but really, you MUST get him in training, be patient and stay consistent.
It also sounds like he has tons of energy which is good but he has no way to release it. What kind of exercise does he get bc I doubt very much if he will be happy being a couch potato. He sounds like a fun normal rottie that just needs guidance and most of all training. Don't ever expect him to do something or behave in a manner that he was never taught. Simple solution, make sure he gets plenty of exercise so he's not bored and first and foremost enroll him in a beginners OB class if you're not already doing that. Keep your cool and be patient. It will come but it won't happen over night. I know you can do it just take one step at a time
. Best of luck to you.
Judy