White isn't allowed to bounce creatures opponents control. Is the effect on Angel of Serenity/Aurelia's Vindicator (exile then later return to hand) a bend/break?

It’s not exactly bouncing them. It’s exiling them for as long as the card remains on the battlefield, and only when the card leaves play return them to hand. This is done to allow the return of cards in the graveyard to the hand - something white normally does. The exiling and return to hand is a bit of a bend, but it’s not the same as a direct bounce.

Mr. Rosewater, please don't give White card draw. White is my favorite color. I acknowledge that it has shortcomings, but it is fully my belief that White's mechanical identity would not be helped through card draw. Instead, its shortcomings (namely card advantage) can be solved through other means. White has access to tools like Reveillark, Angel of Serenity, and Ignite the Beacon that can easily be used for card advantage instead of watering things down by simply adding cards to your hand.

Our goal is to solve white’s issues in a way that plays into what white cares about philosophically. We have no intent in undermining its weakness.

If the reason dragons are included in every set is because they're the most-demanded creature type, then how come nearly every one that Wizards makes is overcosted and unplayable? As compared to, say, angels -- most of the angels printed have use in constructed (Restoration Angel, Sublime Archangel, Angel of Serenity, etc.)

Perhaps the target audience of dragons isn’t the tournament player.  Also, we have made a few constructed dragons over the years. For example, Kai Budde became world champion with one (Covetous Dragon).

Why does Angel of Serenity have two swords in her art, but not First/Double strike?

Not every sword carrier has first/double strike.