Weasley family ages

[Molly]

No: HPFGUIDX 42237

I'm working on a fic, and I got about one line into it
before I stopped and went, "But how old ARE they?", which led to much
scribbling as I attempted to figure out the general age divisions of the
Weasley clan.  So far I have:

Ginny is approx. one year younger than Ron, who is approx. two years
younger than the twins, who are approx. two years younger than Percy.
Percy, it seems, is approx four years older than Ron. Ron says that
Gryffindor hasn't won the House Cup in seven years, since
Charlie was on the team, so Charlie has to have been out of Hogwarts
seven years when Harry&Co. start, making him at least thirteen,
fourteen years older than Ron (assuming he played Quidditch his last
year at Hogwarts).

Bill I have no idea about, and I think it's assumed he's older than
Charlie, but is there evidence for this?  And why the big gap between
Charlie (if he's younger) and Percy?

I think I've figured out most of JKR's English historical references in
the Weasley family might be (just kind of guesses, I haven't researched any
of this): Arthur - King Arthur, Percy - Knight Percival (or
Percival the Fool (hmm)), Charlie, Bill & George - all Kings of England,
Molly - Mary, Queen of Scots, Ginny - Guinevere, Fred - Lord North. Ron -
I have no clue.

Thoughts?

- Molly,
newbie from WI