Brian D: There really isn't a magic fairlead position because the wind is ever changing as is the sea and the point of sail. That being said, you can get in the ball park. When you look at an average fairlead track it is probably 6' to 8' long. In most closehaul situations you use probably only 2' of the track. So if a mate didn't want to mess with the jib fairleads what he would do is determine the oustside parameter of the track usage and mark them with a piece of tape or something and then pick a middle point. I can tell you that the wind won't alway cooperate and in some case your jib will fall out of shape and you'll have to adjust it.
On the main, if you don't want to adjust it then set the traveler at about the center line of the boat.
Obviously, I love to have my sails nicely shaped. What I do when I'm just out fooling around with guests is I keep one eye on them and one on the sails. You would never know what I'm doing. In other words, in the middle of the conversation, I'd still be concentrated on what your saying but I'd reach over and adjust the fairlead or pull the traveler - just to keep the boat on an even keel and my sails liking me - they hate me when they get out of shape!!
Sail trim is fun and after all it is a sail boat and not a power boat. This is just a general observation but I hear a lot from sailors that they don't want to tweek the sail trim controls. They tell me this when they were calling me to come on board with them for some sail trim pointers. Actually, they do want to tweek the sail trim controls but they just arn't sure what to do. Once they learn how easy it is they are hooked.
Brian D, instead of the main halyard, consider a Cunnigham. It is easier to adjust and more precise.
By the way, that is a great picture of you behind the helm.