Chimera Kennels

After following many of the posts on this forum for quite some time I have found that my views on breeds and the expectations of them has considerably changed. With that being said I am a school teacher with of course a limited budget but have taken a liking in a serious way to the Swinford type dogs and also to working/family dogs in gerneneral.

I have a question or two that i would like some guidance on though. I am currently doing a good deal of obedience and off leash stuff with my rottie and generally he is taking to it pretty good. We have canine good citizenship award and went for Therapy dog but he didnt pass the section when i had to leave the room for 3 minutes... since then i have gotten that fixed in training.

I have been working him on ball drive for a long time now and he's on 10 for a ball considering his size. I wanna do protection though and i fear that i have spent so much time telling him NO to most aggressive and dominant actions that he will not even engage to pull a rag out lof my hand. he is as dominant as you would expect the average male rottie to be but he just doesnt have the stick wit it ness to play tug or anything but im almost certain that i've broken him up from that in training as he was a real booger when i first got him. pushy, and edgy to say the least. Now the neighbors kids kids ask can he come outside to play fetch,...crazy.. he very much does his job with the yard though as he discerns very well if a kids ball comes too close to the fence... This Is Not A Threat.

questions

1. Whats my first step to working him up to a sleeve?

2. And is there a date on adult dogs that deems them too old to be seriously worked?