In general, 3/3 Moonglow in tier two of Balance is considered a required talent. As such, you get 3/3 Nature's Grace and 2/2 Nature's Majesty since the Starlight Wrath talent has no benefit at all to Restoration. Typically the remaining 2 points which you can allocate outside of the Restoration tree will go towards 2/3 Furor for the most efficient build, however if you find yourself ending fights with extra mana you may want to invest those points in 2/3 Genesis instead as the Genesis talent would be stronger than any alternative for those points in the Restoration tree.
As for casting Insect Swarm, Moonfire, or any damaging spell, that simply comes down to you not being required to heal and having extra mana which can be spent towards damage. Otherwise you should only be getting Nature's Grace procs from Regrowth (which will generally only be used under the effect of Omen of Clarity).
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.