Question regarding focus and strafing

Got two questions:

1.
I still have the A and D keys bound to turn. I know this is frowned upon. In battle I never key turn though. When holding the right mouse button clicking these same buttons will make you strafe.

This discusses the issue: Attacking on the Run: Strafing - Warriors - TankingTips.com

My question is - is there a big downside to this? For those of you who have these keys bound to strafe, don't you still need to hold the right mouse button in order to turn the character and make sure you are still facing the opponent? There is something I am not seeing here... Is there a difference?

2.
How do you prefer to use focus target? On healer (for Intervene), or on enemies?

I can't answer #2 being a pally, but for #1 strafing sideways leaves the mob in front of you in most situations which means that your attacks can still hit it.

I use default setup for turning/strafing a/d for turn, q e for strafe. I don't really use a and d, but it is nice for dalaran moonwalking in a circle

I don't use focus really ever while tanking, no real need for it

I use focus targeting on fights like thorim hardmode where i need to see the tank I am taunting off.

^-- I use Target of Target for that, Can't really see anywhere focus would be useful still

The only time I seem to use focus now is for watching the Spriests MC on thorim and on algalon himself, since i generally have other things targeted when not tanking them so makes being able to see when i need to switch and targeting easier.

The only time I use focus is a healer in 5mans, or a healer in Thorim's arena just so I can keep a better eye on them.

Well, one use for Focus that I was contemplating was in a fight with spellcasters (especially if he won't go down immediately, like heroics where he could be a boss with adds. Or with multiple spellcasters in a group). You could focus the spellcaster just to make sure their portrait remains visible while targeting other enemies. If they start casting you would know even if targeting the add and could do a Heroic Throw, Shield Bash or put up a Spell Reflect...