The Summon Nature's Ally spell mentions:
This spell summons a natural creature. It appears where you designate and acts immediately, on your turn. It attacks your opponents to the best of its ability. If you can communicate with the creature, you can direct it not to attack, to attack particular enemies, or to perform other actions.
A summoned monster cannot summon or otherwise conjure another creature, nor can it use any teleportation or planar travel abilities. Creatures cannot be summoned into an environment that cannot support them. For instance, a porpoise may only be summoned in an aquatic environment.
The spell conjures one of the creatures from the 1st-level list on the accompanying Summon Nature’s Ally table. You choose which kind of creature to summon, and you can change that choice each time you cast the spell. All the creatures on the table are neutral unless otherwise noted.
As a 7th level druid you get access to "Summon Nature's Ally IV" which gives you access to creatures like the Unicorn. A Unicorn comes with interesting qualities such as:
Darkvision 60 ft., magic circle against evil, spell-like abilities, immunity to poison, charm, and compulsion, low-light vision, scent, wild empathy
And special attacks such as:
Turn undead 13/day, smite evil, spells
Does this mean a Unicorn that is summoned with Nature's Ally IV has access to these qualities and special attacks and the druid that summoned it can use its special attacks such as turn undead, smite evil and all the spells the unicorn can cast?