Your best bet is to make an alt and STF it. (You can then freely respec it until you find a build you like).
As for gear, I'm not sure what the weight limit is for no WPF penalty (might be 10).
I try to stick under 10 weight for my armour.
Horse wise, I like to use an arabian whenever I can (I loomed it to +2), but only my Yumi build can ride it.
I spend most of my time on a saddle horse with my Horn bow alt. (I try to make a little money)
But it would work well on a destrier or courser. (Or heavier if you have cash to burn ;))
Bow wise, I use a horn bow on my alt and a yumi bow on my STF (different builds required). Either way you'll probably need bodkins to do any real damage.
Level 30
Strength: 15
Agility: 24
Archery WPF: 172
Weapon master: 8
Riding: 6
Horse archery: 4
Power draw: 5
You can also take this build to level 33
Level 33
Strength: 18
Agility: 24
Archery WPF: 174
Weapon master: 8
Riding: 8
Horse archery: 4
Power draw: 6
It's now a Yumi build!
Level 30
Strength: 18
Agility: 21
Archery WPF: 163
Weapon master: 7
Riding: 7
Horse archery: 3
Power draw: 6
Again take it to level 33
Level 33
Strength: 18
Agility: 24
Archery WPF: 174
Weapon master: 8
Riding: 8
Horse archery: 4
Power draw: 6
Even though the Yumi has less HA, I haven't really noticed a difference. I probably can't do mid - longrange shots as easily, but as a HA, you probably won't want to.
You will also draw the bow slightly slower, and the arrows won't fly as fast. Makes it slightly more difficult to have a HA/HX/archer duel when you have a Yumi.
But this is all offset it my mind by the very tasty damage. Admittedly I spent most of my Horn bow time with barbed arrows, and all my Yumi time with Bodkins. (So the difference in damage may not be all that great)
Again, it's worth testing with a STF to find which best suits you. There is also plenty other builds which allow some melee prof, so you won't die as much when dismounted ;P.
Loom wise, I could guess, but I've never loomed a bow or arrows.
I would probably loom your bow first, as you can then mess around with different arrows (You probably won't switch bow regularly).
It's good to loom a horse too, they get some pretty nice stat boosts from looming.
Armour looms would probably be my last port of call, you won't survive that much longer in loomed light armour vs light armour.
Hope this helps.
