help.

I've been neglecting my blog so much lately. I don't know why, it's such a great record of our family life and is immensely helpful when I make our family yearbooks! 
So I'm trying to get back into the habit of blogging more, just my daily thoughts and whatevs.
And I'll start with this post.
I need help.
Major, major help.
Juno is three. Until a few months ago, she slept from about 7:30-8:30 and took a 2-3 hour nap every day. Then, all at once, she dropped her nap and started waking up at 6 am every day. So she dropped 4+ hours of sleep pretty much overnight.
Most days she doesn't really need a nap (she can get by without one) and she still naps inconsistently--maybe twice a week. But getting up at 6 is really hard on the whole family. She won't play quietly in her room, so I spend the 6-7 hour getting up every 15 minutes and telling her to be quiet, leave her sisters alone, etc. We've tried putting a door lock on her doorknob so she just can't come out, but she can still open the door with it on.
I'm not totally opposed to getting up at 6 because at this point, my body now thinks that 6 is the time to wake up so I am not super tired, but it just makes the day so long. The only thing I can think of to do with her at that time is to watch tv and since she doesn't nap anymore, I need her to save her tv hours for midday when I need a break. Getting up for the day at 6 makes our days 1000% longer. It somehow adds way more time to fill than just an hour, I don't know why. It's really tough. I'm especially worried about how that would work when school gets out for the summer and I don't have anywhere to send my kids at 8:30. 
So, that's my first problem: how on earth do I readjust my expectations to starting my day at 6 am? What can we do that early in the morning??
My second problem is quiet time/naptime. 
I absolutely have to have 2 hours to myself in the middle of the day. It is necessary for my mental health and the well-being of my children. It will only get more important when I have a newborn in 3 months. Unfortunately, I have a really hard time relaxing when Juno is awake because I worry about what I will find when I come back downstairs. She's not the best about just watching tv and not destroying things. Also, her sister Helena is a bottomless pit who thinks you have to eat while you watch tv and will come in my room and ask me for a snack every 20 minutes of our 2 hour quiet time. I don't want her to eat a snack while she watches because a) it will be a huge mess that I have to clean up and b) she will still expect a snack at 3:00.
How can I make my kids quietly watch tv for 2 hours without constantly coming in and bugging me? Is 2 hours just too long? Do I need to readjust my expectations to 1 hour?
Please, throw advice at me. I am really stressing about how I will handle a newborn when I am getting up so early and not having a good mommy break during the day!