But I want to play a support paladin/bard. Like a magic marshal. I want to be able to sing as I smite my foes. Ally, once we level up, I would like to use a homebrew prestige class taking bits from the Orator, Divine Crusader, etc. to make a bard-paladin prestige class about righteous fervor and inspiration.
You know, you could just take levels in Marshal from the Miniatures Handbook and then go into Mythic Exemplar down the Charisma path. It does... exactly what you want. Alternatively (or at the same time) go into Warrior Skald for a level or two from some Faerun book, but that's 3.0 stuff. (Not updated, though.)
As for the mounted combat, I recommend
having a horse, if you want one, but using it all the time is just impractical. They refuse to go underground, they're hard to maneuver in hallways... you really need to be outdoors. With our path thus far, I wouldn't count on many open-field slugfests.
Time for my thought of the day. Found a really good way to kill casters.
Me too! I just came up with a build that gets +95 to Hide and Move Silently as well as immunity to all magical and mundane forms of detection* without using any magic himself, and he can activate a dimensional lock effect as well as an antimagic field to prevent teleportation. The stabbing takes a little bit, but enough Black Lotus Extract speeds the process.
*Normal sight, darkvision, low-light vision, blindsense, blindsight, mindsight, lifesense, lifesight, earthsense, tremorsense, scent, detect magic/arcane sight, detect poison, see invisibility (trick, he's not actually invisible!), and even direct psionic mind probing.
(My brother tasked me with creating a level 10 character to kill Vecna, the undead god of magic. The other option was a hyperpaladin using shenanigans to permanently destroy undead a la Hunter of the Dead with an insanely boosted Turn Undead ability.