The Devi or Devi's age is purely dependent on the vessel they are incarnated in. They mature at the normal rate however once they begin to show signs of their celestial ancestry they can appear to change their age at will. They effectively could live indefinitely unless killed.

Much of the alignment of the Deva and Devi is depend on how they grew up and their background.

This can be discussed with your DM, however depending on the vessel that is chosen they tend to favor more fair and medium sized humanoids when incarnated.

Your base walking speed is 30 feet. Your base flying speed is 25 feet.

The Deva and Devi are resistant to radiant damage, immune to being charmed, have magical dark vision, and can use telepathy once per long rest.

You can speak, read, write, Common and Celestial. 

Use one action to activate this transformation.

Your physical statistics change to increase your combat prowess, however,  much like Wild Shape in druids, you retain your Intelligence, Wisdom and Charisma scores. For the duration of the Angel Form: your Strength, Dexterity, and Constitution modifiers become equal to your proficiency bonus; your AC becomes 10 + twice your proficiency bonus; your size becomes medium; your walking speed becomes 10 feet times your proficiency bonus; you gain aetherial wings, giving you a fly speed of 20 feet times your proficiency bonus; and you gain a number of Temporary hit points equal to twice your Class level + your proficiency bonus, which you lose any you have reminding when this Angel Form ends.

You may attack a number of times equal to half of your proficiency bonus(rounded up) whenever you take the Attack action and attack with this weapon. You use your spellcasting modifier for the attack and damage rolls.

You gain resistance to necrotic, radiant damage; and bludgeoning, piercing, and slashing damage from non-magical weapons. You cannot be charmed, frightened, poisoned, or suffering from any levels of exhaustion. If you were suffering from any of these conditions before you transformed, then all of those conditions are removed for the duration of this transformation.

Upon exiting this form the Avatara suffers 3 levels of exhaustion, this effect is cumulative. 

You have the ability to cast the Dancing Lights cantrip at will

Your Wisdom score increases by 1, and your Charisma score increases by 2.