Miriam's questions and bad dream

Miriam is turning into a little girl so quickly. She is beginning to think outside of the box, and is able to express so many thoughts and feelings.
On the way home from church she was so inquisitive. Wondering things like, "is there one sky or two skies?", "does it wrap around", and thinking that "the sky is square." She wondered how she can see it and it looks the same no matter where she is. She wanted to know about angels. Apparently she thought all angels are people dressed in angel costumes like she sees at the live nativity at Christmas time. She wanted to know if we'd go in our car to get to heaven, or if we'd at least go to heaven in our car. "How will we get around in heaven if we don't have a car? Is it small?"
How do I even begin to explain these things to her?
Miriam had her first really bad dream today at nap time. She came running from her room crying saying she had a bad dream. Usually it stops at that, I comfort her and she is fine. But, this dream obviously bothered her for the rest of the day. It is the first time she's ever been able to tell me what she dreamed about. In her dream soldiers came and were trying to take Michael out of our house. She says that I was there and she was trying to tell me about the soldiers. (No more David and Goliath stories for awhile I think) Later she asked me if adults dream like kids, and I said that everyone dreams. She said, "my dreams have pictures, do your dreams have pictures?" All night she kept thinking of other questions to ask me, she was obviously worried. She wanted to know if soldiers go to heaven, so I had to explain that there are good soldiers and bad soldiers. Up until her internalizing the David and Goliath story that she's heard a thousand times, she thought all soldiers were good and worked to keep her safe like Uncle Nate. Then she wanted to know if Uncle Nate carries a sword!
Last week she told Rob that David protected his people from the Philistines like Jack-Jack (the donkey) protects the cows!
I think she's going to be an over thinker like her Momma!
It is so hard to answer her questions in an age appropriate way while neither telling her too much and worring her with stuff she isn't ready for or brushing her questions aside and telling her not to worry about it. I want her to ask her questions and feel validated. And boy does this girl have a memory, she remembers everything I tell her, so I know I need to make my answer a good one and plan on sticking to that answer!