I would put 1, 2 and 3 up, and I'll tell you why. A friend of mine is hunting for a filly, and some of the pics these folks send, blow my mind. And as some of you know, I'm hunting for a mare or two more, and I'm like, good GAWD almighty people!!!! Jeesh.
Because you show performance, you need performance shots, and you also need a full profile shot conformation shot. You'll needs tons of her front, rear, both sides, set up like halter or showmanship, whichever you prefer. People are going to want videos on her, so you better get that started, have her doing whatever you're going to sell her as. For instance, if it's showmanship, video you doing a pattern with her; if it's WP, same with that, etc.
The point is, when you get an e-mail, you need to be able to send them immediately whatever pics you have that they're asking for. If you wait a couple of days, you may lose the sale, and they'll go on to another horse. So remember that.
As far as advertising... I'd put him on Dreamhorse and Equine.com, and if there's some other website that people up north usually use... I can't think of the name of one of 'em, but I'd put him on all of 'em - more exposure, quicker sale.