I agree with Freedom.

Easy answer is to ignore him when he gets excited and reward him when he's relatively calm. You may feel mean ignoring him, but if you pet him when he's bonking you upside the head, you're rewarding him for being overly physical. All dogs are allowed to be excited. That's normal and healthy. But bumping into you, demanding to be in your lap, and excitement urination are not healthy behaviors. If you ignore him when he's excited and reward him when he's calm, he will stop peeing and the other behaviors will subside.

Re: training - same thing. At one point in your day, Brutus is at a controllable level. Train him during this part of the day (late evening may be a good time). If he's getting overly excited, cross your arms, look away, and ignore him. Train him when he's gotten a grip on himself. Tough love

Also, the process of getting up/laying down repeatedly will not necessarily exacerbate arthritis. It may cause pain, but it's not necessarily "bad" for his joints the way you were describing. Running on concrete and stairs and strenuous exercise may impact Brutus' joints, but getting up/down has very little effect on the joints themselves.