Hi J.,
As you know the most important thing is to be consistent no matter what! Instead of talking to or at him start asking him to come up with alternatives. You will have to guide the conversation with prompts but leave it up to him to come up with his own thoughts.
For instance; I could use your assistance. As you know, one of my concerns is that everyone here, not only to have fun but also to be safe. What are your ideas on safety? Can you tell me why it is important for everyone to observe the safety rules? What can you do, as the oldest, to make sure you and the other children stay safe?
Ask the questions and then listen or prompt for more ideas. Don't give the answers outright but if he doesn't get it, just guide him by asking "do you think that this might work better? or that?"
As with the homework do the same. Inform him of his choices and the consequences, then ask him what he thinks should happen.
There's a book called "how to raise a thinking child" and "how to raise a thinking teen" that I read many years ago that gives some great techniques for assisting kids to think for themselves and to make good sound dicissions. I highly recommend it!
When you give a child the freedom to think and come up with their own answers, it puts them in charge and in control of themselves. At 7 years old he is in control of himself and making his own decissions, so assist him in making the right choices for himself and others but putting him in the drivers seat!
Keep in mind that this technique also teaches respect. When you show him that his opinion counts and is important, this shows him that you respect his thoughts, actions, ideas, etc. and in turn he will respect you even more!
Besides...he just might come up with the perfect answer or solution to the issue!
Be blessed and be a blessing!