Matthew,
The ammonia spike you experienced after adding the other rock was probably due to the rock not being cured. Before adding new rock, always cure it in a tank that does not have livestock in it.
As for how fast should you add corals and fish depends on a few factors. A 10g nano is small and will only hold so much stuff, so you have to do some research on the size the corals and fish you think you want to add will eventually grow. You also have to consider the amount of light you have on your tank and if it will be enough for certain corals. Also, many anemones will grow quite large and will require halide lighting (from what I read, I do not have one), so adding one of these may not be a good idea.
Really, there is no magic formula for when to add corals and fish, but I would wait another month or so before doing so, especially since your tank is so new. Keep feeding the animals you have in there now, but don't overfeed.
I hope others will offer their opinions on stocking nano tanks. You may wish to ask your questions on the Nano Forum for more accurate advice.
HTH
