Are Daniel and Charlotte close in age? If they are can't we assume that when Charlotte is a little girl living on the island, while Daniel's mother is also living on the island in the during the same time, that Daniel also should be on the island.... if not, where is Daniel?

Perhaps he is with Widmore

...if not, where is Daniel?

If anything, I thought Dan was older than Charlotte, so he should be somewhere on the island, assuming that Ellie is his birth mother.

I too am guessing Dan was older than Charlotte, but we don't know that he is on the island or ever was. Remember Ben saying Charles often left the island? Whos to say Dan wasn't brought up away from the island and Eloise isn't able to leave like Widmore? Having said this, it does make you wonder how they got off the island, if this is the case. Unless they had their very own sub, and were not stealing Dharma's...

I too am guessing Dan was older than Charlotte, but we don't know that he is on the island or ever was. Remember Ben saying Charles often left the island? Whos to say Dan wasn't brought up away from the island and Eloise isn't able to leave like Widmore? Having said this, it does make you wonder how they got off the island, if this is the case. Unless they had their very own sub, and were not stealing Dharma's...
That's very privileged information" ;)
From "Jughead:".
RICHARD: [chuckles] I'm not sure what you are expecting me to say, John Locke.
LOCKE: I expect you to tell me how to get off the island
RICHARD: That's very privileged information. Why would I share that with you?

I like to think the next scene that immediately follows Daniel getting shot by Ellie is Ellie coming home and having a talk with Daniel at the piano (making Daniel about 8 or 9 at the time).

I like to think the next scene that immediately follows Daniel getting shot by Ellie is Ellie coming home and having a talk with Daniel at the piano (making Daniel about 8 or 9 at the time).

I think that makes sense.

Are Daniel and Charlotte close in age? If they are can't we assume that when Charlotte is a little girl living on the island, while Daniel's mother is also living on the island in the during the same time, that Daniel also should be on the island.... if not, where is Daniel?

They may both be on the island in 1977. But if Daniel is, he would likely be with the Hostiles.

While a young Dan could possibly be on the Island with the Hostiles the show would be contradicting itself. When they were time traveling they got the nosebleeds in the order that they were on the Island first... Dan's nose never bled while they were... or maybe it did but only at the end of their time traveling adventure. So we can reasonably hypothesize that Danny boy has spent the least amount of time on the Island (a total of less than a month) or that he is like Locke... but most likely he is not on the Island at this time or has had some kinda other protection with that.

While a young Dan could possibly be on the Island with the Hostiles the show would be contradicting itself. When they were time traveling they got the nosebleeds in the order that they were on the Island first... Dan's nose never bled while they were... or maybe it did but only at the end of their time traveling adventure. So we can reasonably hypothesize that Danny boy has spent the least amount of time on the Island (a total of less than a month) or that he is like Locke... but most likely he is not on the Island at this time or has had some kinda other protection with that.

Dan had a Constant.