Dear god I cringe reading this... Here's a way to give you a rough idea what it feels like:
Stand with your feet shoulder width apart, both facing straight ahead. Now do a half squat and try to rotate and bounce lol... I'm doing this in my office and must look retarded! Anyway I can turn my upper body about 45 degrees in either direction before I get some serious knee pain.
Now keep your heels where they are but lift your toes and rotate your feet so they're just slightly toed out \---/ and try it again. I can turn probably about 60 degrees in each direction that way.
For what it's worth, +15-15 may be too wide for some people. I like to keep angles between 18-24 degrees apart but that's my taste. I ride -9/+9 and used to ride -12/+12. That 18-24 degree spacing works for any binding setup. I had my girlfriend start -3/+15 to help her feel comfortable turning before we changed her to a symmetrical duck stance half way through this year (which she loves by the way).
The "old" stance that every rental board in the early 90's had was usually 0/+18 or so. I learned on this on rental boards for a winter in 92/93, then when I got my first board I set it up the same, but then experimented over a few year period until I found symmetrical duck to be the most comfortable for me.
Also experiment with stance width as this will have a big effect on your riding. I tend to find the reference stancewidths pretty good on most boards I've been on and set up, but I'm heavier than my height should be, so sometimes need to go more narrow.
Yeah just try shit out and see what you like instead of listening to us!
Don't do it at home though. Go to the hill and take a few warmup runs to feel the snow, then use the resort tools or a screwdriver from home to make small adjustments (say a 3-5 degrees per foot at a time) and take it for a few more laps, repeat until you find a good stance angle. Then experiment with stance width. Don't change two things at the same time (i.e. angle and width) or you won't know what change was positive and what was potentially negative.