I would suggest that you bare shaft tune your arrows, you can read about the method if you are not familiar elsewhere in these forums.
Regarding straight or bent, I perfer straight, without locking it out. Remember the most important factor in good shooting is where you point your bow. When you point at something across the room, you have an extended arm. Why would you do differently when shooting a bow.
I know a lot of shooters who use the bent arm, many do really well. It was my understanding that it was a perfered method before bows were designed to eliminate hand shock.
My recures had no hand shock, and my Black Widow Longbows have no hand shock.
Regarding the index finger in the corner of the mouth, I use to shoot that way. I now use the middle finger in the corner of the mouth. It allows for the arrow to be situated a little closer under my eye. This allows the bow hand to point, automaticly, at the point the eye is locked in on.
Just a word of advice, I am not sure how long your arrows are, but I am shooting 2016's at 55 pounds with 175 grain tips, you may want to try a little heavier point weight.