Wow I kinda giggled as I was reading your introduction. My brother and I, he’s 2 years younger then me were exactly like that! We would get up before anyone else and hard to tell what we’d get into! We made breakfast one morning of corn flakes and just about everything else in the fridge.. needless to say it was a mess! partners in crime and boy did we ever get into trouble.. often.
We’re both ADD. He’s not so much and seems to have coped allot better then I did.
We were highly intelligent kids that got bored allot.. My poor Mother always tried her best but there was no way. Even our Dad was away allot being a Fisherman he would go out for a week or so, comeback for a little then out again.
What I’d recommend. Routine. Same time to bed. If they don’t go to sleep right away then as long as it’s dark and quiet let them be. Maybe take the toys out of the room and have it a place for sleep only.
And as for the getting up before you. Get those ringers that go off when the door is opened. It goes off, they can’t sneak out, no more fun. Put the buzzer part outside your door so they hear it as well as you do so they know they’re caught 
Hope this helps some.
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