1. On my chest, but you know, I've never paid attention to where exactly. Most of the vids I've been looking at say on or below the nipple area. It's probably something I have to get used to by practicing more often.
2. Not on my heels, that's for sure. I didn't know about that until this past weekend. I'm usually grasping the bar during the entire movement.
3. I think they're flared. I've never quite gotten the whole arms 45-degree angle thing.
This vid -- http://www.youtube.com/watch?v=vUcjOIZc80c -- mentions something about an elbow correction. I'm not really clear on it. Just saw it again ... am I rotating them slightly outwards and do I keep them rotated for the duration of the set?
Do people usually bench with their feet on the bench or on the floor?
Benching with your feet on the bench is a bodybuilder trick to target the chest more; fuller range of movement and no leg drive.
Great thread lots of useful pointers
It is a long read but maybe some things in there could be helpful...it does address the issues of numbers 1 and 3 in your above quote.