Autograohs can be tricky, esp before practices when there are big crowds. The best place to be is just across Oneida street as the players cross from Lambeau on their way to practice. If your kid is nice and asks politely, a guy or two will almost always stop and sign quick.

As for the bike riding, you can participate but you have to get there very, very early. There's a lot of waiting and even then there's no guarantee your kid will get picked, esp as camp goes on as guys tend to find one kid early and stick with them. But it random bike rides do still happen occasionally.