overwatch
Ana is Overwatch's Support sniper who shoots people to heal them.
Like Widowmaker, Ana has a scope. Unlike Widowmaker, Ana doesn't seem to get any benefit from scoping, other than the zoom.
Can Ana's biotic rifle shots land headshots? I notice that she doesn't have a "Critical Headshots" stat tracker either…
Yes, it's fully compatible with Steam Controllers. You'll be at a slight disadvantage against keyboard/mice players, but it should still work fine.
Here's an example of a player using the Steam Controller to play Overwatch. Appropriate buttons can be mapped in the Controls settings.
To actually get Overwatch compatible with the Steam Controller, it must be run through Steam, so:
Games -> Add a Non-Steam Game to my Library
Note that this will also cause you to have two clients running, both Steam, and Battle.net, so you may want to avoid setting up a controller if you have issues running both clients at the same time.
This is just an overview, but reddit user /u/malecden has a very good setup tutorial listed here on reddit. in order to get the Steam Controller functionality to work with OW.
Allied projectiles will go through Reinhardt's shield without difficulty. There is no friendly fire in Overwatch, but your own splash damage abilities can hurt yourself (Junkrat and Pharah most notably).
Also note that there are a couple of enemy projectiles that penetrate his shield, see this question for a complete list: Does Reinhardt's shield block all abilities?
The actual players can also pass through the shield without difficulty, both enemies and allies.
Best Answer
I'm assuming you mean critical hits on headshots. There's no explanation other than no - she will not get a critical hit when landing a headshot.
Source: http://overwatch.gamepedia.com/Ana