An endless array of shot lengths, lies, trajectories and stopping distances can make your short game confusing. You can simplify all of this, however, by using the next month to practice what I call a "reference" swing. With any wedge, take your hands back to just below hip height using a full wrist hinge and finish all the way through like normal. That's it. Learn no more, but practice this swing enough to be able to repeat it consistently, with the same backswing length at the same rhythm and with the same follow-through.
By using the reference-swing concept with each wedge you carry (and I recommend you carry four), reference-distance shots will become a strength of your short game. Learn another length backswing to add four more well-controlled shots to your arsenal.
What's more important to producing spin: your wedge's face grooves or pinching the ball hard against the turf? If you answered "both," you're correct. But make no mistake: face grooves are super-important. Wide and deep grooves funnel off water and grass to improve clubface friction, and sharp-edged grooves help by digging into the ball. The higher the loft, the more important grooves become. If you're looking to add even more spin, add speed. The harder (faster) you hit any given wedge, the more spin it will produce.
Tweaking Your Stance
There's a perfect stance, but it varies for each shot and player. A narrow stance allows you to rotate your body around your spine with less resistance, but it may not give you the stability you need or a base solid enough for you to produce power. As your feet get farther apart, you can generate faster swings until you get them so far apart you lose the ability to turn around your spine. I recommend a stance slightly less than shoulder-width for most finesse shots, but it's up to you to experiment and find what's most comfortable and effective for you.
The percentage of times a PGA Tour pro will make a 35-foot putt, just like the one Woody Austin drained on the final hole to win the Merrill Lynch Shootout with teammate Mark Calcavecchia last December. To put this into clearer perspective, mid-handicap amateurs can expect to make this putt only once out of every 105 attempts.