Dragon Gaining Levels

[Matafuego]

Suppose a Wyrmling Gold Dragon adventures with a party.
Does he gain experience?
And if he's a cohort?
Can he gain Paladin or Fighter levels?
How does it work when he "ages"??

I have this question and cannot find answers to it.
Could anyone help me please?

 

[Wippit Guud]

http://www.wizards.com/d20/files/v35/MonstersasRaces.rtf

 

[Matafuego]

Yes, I understand the ECL rules but...
"Level Adjustment: Wyrmling +4; very young +5; young +6; others —"

Wyrmling M 8d12+16 AGE 0–5
Very young L 11d12+33 AGE 6–15
Young L 14d12+42 AGE 16–25
Juvenile L 17d12+68 (178) AGE 26–50

So a gold dragon begins as a 12th level character, 8 hit dices and an ECL +4
Supposedly he gains a few Paladin levels in five years, let's say 3, then he is a 15th level character and when he ages his ECL becomes 1 higher, so he's a 16th level character, but he gains 3 hit dice so he's a 19th level character???
And when he's a Juvenile and has no ECL listed???
The aging thing is what loses me, since we're planning on playing this party for a looong long time.

 

[Korak]

Yes, I understand the ECL rules but...
"Level Adjustment: Wyrmling +4; very young +5; young +6; others —"

Wyrmling M 8d12+16 AGE 0–5
Very young L 11d12+33 AGE 6–15
Young L 14d12+42 AGE 16–25
Juvenile L 17d12+68 (178) AGE 26–50

So a gold dragon begins as a 12th level character, 8 hit dices and an ECL +4
Supposedly he gains a few Paladin levels in five years, let's say 3, then he is a 15th level character and when he ages his ECL becomes 1 higher, so he's a 16th level character, but he gains 3 hit dice so he's a 19th level character???
And when he's a Juvenile and has no ECL listed???
The aging thing is what loses me, since we're planning on playing this party for a looong long time.

There are detailed rules for this in the Draconomican. Basically, the dragon must use a certain amount of xp to gain its dragon hd advancement as it ages, and must take these "levels" in dragon at certain times.