(Alright Zoethezany was this the last on your list? Or were there more?...)

1) his brothers often play connect the dots with his freckles when he's asleep (which makes for a very grumpy Seamus later on).

2) his favorite mythical being is not in fact a leprechaun but a clurichaun (which spreads bad luck), second favorite is a skin-walker, and third is a centaur.

3) he always carries around a small dagger.

4) his favorite animal is a horse and he goes horseback riding daily (if possible).

5) along with fact #4 he also owns two horses:
A black and white Clydesdale named Ríonach (meaning "Queen") and a grey Appaloosa named Dusty.

6) every time he finds a four leaf clover, he gives it to someone else. He never keeps them (unless they were given to him of course).

7) he is known for handing out random solid gold coins to family and very close friends. Where he got them from no one knows. It's a running joke that he either got them from leprechauns or is a leprechaun himself but if asked he'll merely give you a grin with a twinkle in his eye and reply "who knows?"

8) where magic is concerned his best talents are: luck, charms, talismans, illusions, and he is able to copy near any form of leprechaun magic.

9) he is proficient in sword fighting and this is his preferred method of combat. In his youth he was never seen without one.

10) he has always been secretly jealous of Native American Chief's headdresses. (Though he has never admitted this aloud).  

11) his eyes' exact color are a mix of grass green and fern green.

12) he's written a few history books because he couldn't stand the inaccuracy of the ones humans had.

13) he sunburns very easily and because of this doesn't spend too much time at the beach (or out exposed in the sun in general).

14) he has multiple scars on his back from where he was flogged five separate times long ago.

15) he has dracophobia (an irrational fear of dragons).

16) he is badly allergic to poison ivy and poison oak and once had to be hospitalized for accidentally landing in a patch containing both....

17) he lives in what basically looks like a room added onto an old shack with a rugged fence around the length of the property. He has a long garden and a good sized pasture for his horses and a few cattle.
(Note: he does all farming and such by himself and usually doesn't seek out help unless his animals need it or he is somehow incapable).

18) he is so stubborn that once, while fighting a war, he got shot in the upper arm (on his left) but didn't tell anyone how bad it really was. When they got back to their tents he did not go to seek medical aid, he took the bullet out himself (and still has the scar to this day).

19) he's a better magic teacher than his brother, Scotland. The evidence? England...
(Same goes with cooking.....)

20) does anyone recall that good ole Irish luck?
Seamus doesn't have it.
This is because with every gold coin he gives away he puts a bit of his own luck into it to give to the new owner of the coin.

Bonus!!
21) there's a three way tie for whom he's given the most coins to:
Northern Ireland
Canada
Native America