S.H.
You seem to have a good routine for him. I assume he is the oldest child?
I'm not sure how old he is, since you didn't mention that. But, since he is always asking you "now what?" Well, maybe it's because he knows you want him to be 'useful' and he is just being conscientious and/or wants approval for what he did. So that's good.
Or, he genuinely does not know what to do with himself.
One thing you might try is: have a jar, and write down a few things on pieces of paper, so that when he does not know what to do with himself, he can go to the jar and pick something. It can be either "work/chore" stuff, or "fun" stuff, or even just the chance for him to just hang out or play. He seems real 'educated' and is a good student, so 'reward' kinds of things might be a good breather for him. Maybe even things like "write a poem or haiku" kinds of things, or creative things, or the chance for him to work on any "hobbies" he has.
I think its great that he even helps his sister with his homework... most kids don't like to even do that. Its a big responsibility. What a great kid you have!
Or, you can always "teach" him how to think of things on his own... teaching 'resourcefulness' to a child is always a great trait to acquire....especially if he tends to get "bored" and can't think of anything to do.
Or, if he is a "busy body" type and always has to be doing something with himself, then have him do other things... but bearing in mind a kid needs down-time too.
Its great you have him plugged-into things and expanding his mind with good book topics. :)
Maybe even ask HIM for ideas... then you won't have to do it all... and it will give him a chance to creatively problem solve for himself. Sometimes, even just sitting and doing "nothing" is great for a kid... it gives them time for self-reflection... and they "grow" this way too. My daughter comes up with all kinds of things when she does that. And then we talk about it or I tell her to draw what she is "thinking" or dreaming of, or any of her "hopes." Its a great exercise and fun at the same time.
Good luck,
Susan