Dunno if I'll have the time ... but I'll tentatively call Male Venus. 
Reserving male Saturn. -glances at a certain someone-
Female Neptune please!
Reserved... Reserved...
Reserved!Good god am I tempted to go right for Lady Mercury...
-Casually reserves so you can plot- >.>
...Male Uranus...
Reserved.
Okay... Onto the questions!
Going to try to get a character sheet done. Is the school a High School or College?
GM Note: As Amarlo mentioned, the Academy is a University. Characters should be in the age range of 18-22 attending their 1-3rd year in school.
Also, I noticed Saturn does not have a passive... is this intentional?
This was an accidental omission on my part while I was constructing the posts. Will fix this shortly.
On one hand, I am not the biggest fan of school based games...
I wouldn't call this a school based game. A school is a very convenient way to bring people from essentially anywhere into one location where they would likely know each other and or be somewhat familiar with one another. Overall the school will play a very little part in the game aside from being a setting in which everyone is attending... At least to start. That is, if the school is your hold back I really wouldn't bother worrying about it because it isn't my focus beyond being a device to bring the caste together initially... And when the caste eventually moves onto the
saving the god-damn universe attending school just... well it just really isn't going to be on their list of priorities.
Does the character, when infused, gain automatic proficiency (better yet, mastery) with the weapon chosen? Otherwise, I can see the weapon being basically useless/more for show. As even a 'basic' sword requires a lot of practice to truly use effectively.
GM Note: Characters gain extensive knowledge of their weapon as it is assumed that the training needed to utilize the weapon comes from the essence of the planet. Can they get better? Absolutely, but they will know how to use their weapons in combat.
Can weapons have powers, to to speak? Similar in nature to what one might find in D&D.
GM Note: Potentially. It will depend on planet, power in question, the weapon itself... Best to say very small powers, but yes the potential for them to have abnormal traits is absolutely there.
Laying claim to Emily Wickersham.
Noted.
Side note, while both of the same planet have to be together and unified to use their unity power I don't think that means they have to be together relationship wise or sexually also o.O
GM Note: No. The Unity power is more like a combination attack, it's something that both Ascendants are able to summon only when working together to create it. As I'm sure you noted these powers are much... stronger than the attacks I want characters to have at the start and should usually rival, in general, some of the most powerful attacks they get later. They need not be romantically or sexually involved to access this power, simply working in tandem to utilize that power. The Ascendants were strong on their own, but when an Ascendant Pair was working together they were out right frightening.
And then some random assorted stuff...
I go to bed for a couple of hours and holy interest so far! Jeez! Awesome guys. Love it! Bring your friends, lots of roles still open!
GM Note: Ascendants do
not need to be romantically involved with their pair. While it was not uncommon for this to happen it was by no means the rule. The Ascendants were a unit in of themselves, and most often worked as rulers of their own worlds. To this end it was natural in many cases for feelings to bubble up and the pair to become involved with one another however it was equally as common (perhaps slightly more) for them to want to keep a health degree of separation between one another as part of their goal was ensuring that the other did not go off the deep end, so to speak.
GM Note: Remember that each Ascendant is unique in of itself and has no ties to the Ascendants before them. So in the case of something like the Solar King (Ascendant of Sol) and the Lunar Queen (Ascendant of Luna), whom were married before need not have any attraction at this point.