First.
You must execute a power's text in order. So, the attack like must be executed before the hit line, etc.
Second.
The 'Varies' keyword is actually a placeholder. If you choose a damage type for such a power, the power gets that keyword. Moon and Stars has the Varies keyword. The Keyword list comes before anything else in the power, so needs to be sorted out first.
Third.
The keywords of a power can through various means affect the Attack line by granting you bonuses to attack, Wintertouched being a great example by giving you combat advantage when you use a cold power against a creature with vulnerability cold. Which means you must sort out your keywords for a Varies power before you can resolve any Attack lines.
Fourth.
There is only one instance of Attack: in the power, and one instance of Hit: which means that you only select the damage type once. And, as already established, it must be done before the Attack line.