No kits are balanced for the correct amount of yeast and nothing needs adding apart from the ingredients supplied. (Unless you a pimping it up!)
A good stir and a take a reading on your return. Mine finished shy around the 1.015 mark at which I bottled.
This is a good tasting beer, from my notes when I did this I used a single carb drop to every 500ml PET bottle and stored them in the warm for 2 weeks for secondary before moving a cooler location. Tasted great 4 weeks after this, finished after 8 weeks when it really did develop into a great beer.
I do plan to make this again but stick it in the Corny keg, too many other kits to get through first