[3.5] Accidental Supermount Help

[Fuzzy Math]

Greetings, fellow Playgrounders! Coming back to 3.5 after a decade long hiatus and jumping into an epic level game. Already have a character made, but just in case we can't resurrect the big lug, I'm making a backup character that will have a dragon mount. If I'm doing it right, that is. Here is my current build, without magic items:

Dragonborn Halfling (Paladin(of Freedom) 5/Beastmaster 2/Sorcerer(Wilderness Companion ACF) 4/Halfling Outrider 10)

STR: 13 (Base 15, -2 racial)
DEX: 14 (Base 14, +2 racial, -2 DB)
CON: 18 (Base 16, +2 DB)
INT: 14 (Base 14)
WIS: 14 (Base 14)
CHA: 23 (Base 18, +5 Stat Bump)

Feats: Skill Focus (Handle Animal, Mounted Combat, Natural Bond, Mounted Archery, Dragon Steed, Ride-By Attack, Devoted Tracker, Spirited Charge)

I was unaware of the Supermount build until I noticed Devoted Tracker in my books and searched how to apply the feat, trying to figure out how it worked. Lo and behold, it added both Special Mount and Animal Companion together! There's the accidental part covered. I decided, since it's an epic campaign, what's more epic than a knight on a dragon?! So, where I need help is figuring out the dragon and I'll break it down:

1. By taking Dragon Steed, can I qualify for a gold dragon wyrmling at Character Level 12 or does it need to be effective Paladin level 12 or does it need to be a solid 12 levels of Pally?
2. A gold dragon wyrmling starts off at 9 HD; does the 20 bonus HD advance the dragon's age category or is it just a really beefed up wyrmling?
3. If it does advance age category, what would that be? Mature adult or old?
4. Does the Bonus HD grant it stat bumps every 4HD?
5. Does the Bonus HD grant it a feat every 3HD? (If so, would it have a total of 10 feats to pick?)
6. Skills and skill points; what are a dragon's class skills and how do I calculate skill points?

This feels borderline cheesing, having a mount-panion this awesome, but it seems to be within "The Rules" as they are written and my understanding of them. Hopefully I was clear enough in my questions and description; if not, I'll answer any questions when I see them! Advanced thanks for the help!

[Edit] Just realized I forgot to include the levels of Halfling Outrider. Did so and marked edit in red.

[Darg]

1. Effective paladin level
2. Bonus HD are not real HD. The companion/mount basics have definitions of what bonus HD provide: more HP (d12s), 3/4 BAB, saves (fort&ref), skill points, and feats. Dragon type does not apply to these BHD except for the special exception of the d12s (arguably only applies to the paladin BHD). As it doesn't say that creatures can advance through BHD, they don't have permission to. Dragon special mounts also have special progression. A gold wyrmling has 8HD + 2HD from effective paladin level 14. Total HD would be 22. Reduce sorc by 1 and take outrider 10 to get +4 HD instead.
3. Young Adult
4. No
5. Yes. 8 feats from 22HD.
6. "Skill points equal to (6 + Int modifier, minimum 1) per Hit Die, with quadruple skill points for the first Hit Die."

[Fuzzy Math]

1. Effective paladin level
2. Bonus HD are not real HD. The companion/mount basics have definitions of what bonus HD provide: more HP (d12s), 3/4 BAB, saves (fort&ref), skill points, and feats. Dragon type does not apply to these BHD except for the special exception of the d12s (arguably only applies to the paladin BHD). As it doesn't say that creatures can advance through BHD, they don't have permission to. Dragon special mounts also have special progression. A gold wyrmling has 8HD + 2HD from effective paladin level 14. Total HD would be 22. Reduce sorc by 1 and take outrider 10 to get +4 HD instead.
3. Young Adult
4. No
5. Yes. 8 feats from 22HD.
6. "Skill points equal to (6 + Int modifier, minimum 1) per Hit Die, with quadruple skill points for the first Hit Die."

1. My effective paladin level is 15, 5 Pally and 10 Halfling Outrider, if I'm doing this correctly.
2a. My effective druid level is 20; 2 BM (Level +3), 4 Sorc ACF (Level/2), Natural Bond (+3), and 10 HO.
2b. BHD, with Devoted Tracker (again, if I'm reading the feat correctly) would be +20, so 28d12?
2c. Is there a table that lists the special progression?
3. If the BHD doesn't advance age category, how does it go from Wyrmling to Young Adult?
4. Noted.
5. Would it be 10 feats at 27HD?

[Darg]

1. My effective paladin level is 15, 5 Pally and 10 Halfling Outrider, if I'm doing this correctly.
2a. My effective druid level is 20; 2 BM (Level +3), 4 Sorc ACF (Level/2), Natural Bond (+3), and 10 HO.
2b. BHD, with Devoted Tracker (again, if I'm reading the feat correctly) would be +20, so 28d12?
2c. Is there a table that lists the special progression?
3. If the BHD doesn't advance age category, how does it go from Wyrmling to Young Adult?
4. Noted.
5. Would it be 10 feats at 27HD?

1. So character level 21? 5 + 2 + 4 + 10 = 21
2a. See 2c, but if CL is 21 then the companion side is correct but the mount side is incorrect and the total would be 24 HD. You only need an EDL of 18 to get the +12 HD. If the sorc levels were druid instead, you could have +14 HD from the 21 EDLs.
2b. See 2c.
2c. Draconomicon pg 140 table 3-16
3. You said "if" and I answered in case there was a special exception
5. Yes. 1 at 1st and 27/3 is 10 total.

[Fuzzy Math]

Ah, that makes more sense now, thank you! Sadly, no special exception, so I'm stuck with a wyrmling gold dragon for a mount. Granted, a suped-up wyrmling with quite a few feats! Unless there's a way to magically age said dragon up a couple of categories, I might be better off with a different mount. At the risk of upping the cheese factor, does a bronze dragon with its water subtype count as an aquatic mount? I saw the post "New World Record Mount Familiar Companion by HD" and I was trying to figure out how the black dragon listed there counted as an aquatic mount for the Waverider PrC.

[Darg]

By RAW, only a paladin can have a dragon special mount other than the dragonnel. The fiendish servant list is likewise reserved for blackguards.

That said, the dragon steed feat doesn't care where you get your special mount. Any class that has a special mount can have a dragonnel. Waverider only cares that you can ride an aquatic mount. The mount doesn't have to stay aquatic once modified by dragon steed.

I personally wouldn't rule a creature with the water subtype as aquatic, but DMs may vary.