I've never been to the bottom with the fog still there so I'm not entirely sure where it is, but Leeroy can spawn as soon as you're on the narrow walkway on the cliff face overlooking Ash Lake. I was just standing there admiring the scenery when he spawned and jumped me. If the fog door is the small cave entrance after that point then yeah, you can fight Leeroy pre-Anor Londo.
This is the conclusion I'm reaching too, hence my selection of the Black Cleric gear. My basic train of thought was that, hey, Oswald looks awesome wearing it and dual-wielding, I could look awesome wearing it and dual-wielding. And then on top of dual-wielding weapons you throw in dual-wielding Miracles and Sorcery and, wow, double the awesome.
Anymore in PvP I basically never use my shield anyways and just try to dodge everything, so I'll never even miss it. And if I'm wearing little enough armor that I'm full speed without the Dark Wood Grain Ring then I get my ring slot back. Sounds like a win-win.
Only thing I'm wondering is just how much better the Parrying Dagger is for parrying than, say, the standard Dagger. Going Parrying Dagger means 14 Dex is needed, regular Dagger I could use with the 10 Dex I'll need for the Barbed Straight Sword. That's 4 whole stat points saved right there.