I'd go for dragon wildshape over frozen wildshape - it's more versatile and makes you much more mobile, and if you're more summoning-focused that's what you really want anyhow.
Again, natural bond isn't really worth the feat compared with your greenbound summons. I'd much rather be able to get them out faster (Rapd Spell) or improve their Str/Con (Aug Summoning). If you can take a flaw, take 2 by the way, and use them for Aug Summoning, instead of getting Quicken but waiting until 9th before you can use it.
My own druid, by the way (Not summoning-focused, except for post-battle healing - he's basically a generalist):
Fireblood Dwarf Druid 9
Feats:
1st: Improved Toughness (Lots of fireballs and glass cannons in this game, so even with 20 Con and this feat, the character still dies occasionally)
3rd: Companion Spellbound
6th: Natural Spell
9th: Craft Wondrous Item (The game has TONS of gold (500,000g at 9th level I think), but almost no item shops, so this is me taking one for the team. Plus, they need some buffing anyhow)
(Planned: Quicken Spell, Frozen Wildshape, Rashemi Elemental Summoning. I'd go for dragon wildshape, but there are no dragons in the campaign world, so cryohydra it is...)
Favored wildshape form: Cave Triceratops, Ankylosaurus, Fleshraker (He's a dino-themed guy)
AC: Ankylosaurus (I'm avoiding Venomfire for the sake of the campaign)