fifi, the weeing inside could be indicative of a health problem, although it is probably anxiety. I would get him checked over just to rule it out.
I have a few snippets of advice, probably repeating whatever has been said already.
With regards to the pulling, try this - i saw the guy on dog borstal doing it and thought, what a prat, that'l never work - well i soon ate my words, i tried it with my dog. You need to be sans buggy for this though, have him on a fairly lose lead, when he pulls, quickly turn and walk the other way, then keep doing it, so that he basically has to look to you to avoid being yanked left right and centre, soon he will be walking wonderfully because he is anticipating you turning round abruptly. It works a treat, no tugging no strength needed.
The hyper boxer - um, well no real advice there, he is a boxer, its what they do. Incredably patient with kids though. You could speak to your vet about this - how old is he? Some people advise castration if he is getting a bit to big for his boots, but i would only use this as last resort. Whilst you are talking to your vet, ask about a DAP diffuser. What it is, is a plug in like an air freshener that releases doggie pheremones into the air that calm dogs down. The pheremones are that produced by whelping bitches. You need to give them two weeks or so, i had one for my mental rottie (he was a rescue and MAD!!) and it seemed to work, although it coudl hav just been him settling down. The DAP might help with the piddling pete problem too. AGain, do get that checked by a vet, he might have a wee infection or something.
ah, just read he is only 12m, thats a teenager then, he may well calm down, but now would be a good time to consider the castration if you are going to chose that route.
I have to admit i was CRAP about taking my rotties out, never had any problems.
He sounds like a normal boy to me, and bloody lovely. FWIW, if you do decide it is too much, he is a DOG, he wont suffer if you rehome him to a nice new home. You'll miss him though, so give him a chance if you can.