Take 3 lvls fighter and then 5 lvls paladin to get a superior mount and then the 9th lvl as a Cavalier (Complete Warrior) and you're set.
Feats you absolutely need are: Mounted Combat, Spirited Charge and Ride-by-Attack. I also like Trample. Power Attack is always great as a frontline fighter, and you should have Weapon Focus. Initiative is not your biggest problem as a mounted character, so I would skip Improved Initiative if I were you.
I do not see why you want the spiked chain besides that it has a cool and nasty feel to it, and it will cost you a feat. You are going to use a lance if you are to make the most of this character.
--- Merged from Double Post ---
Also you want to make sure your character is effective when not mounted as you will inevitably have to dismount sometimes to raid dungeons and rescue damsels in distress...