Most coyotes will show up with in 10 minutes, so just sit on a stand for 15 minutes and surely your friend can skip smoking a sig. for that long. Two of ya hunting, no reason to carry two guns each. One gun a piece should suffice.
There are several factors to concider when deciding how far to move between stands. If you're in an area that is loaded with coyotes, 1/2 mile might be enough distance, even if you fired shots. BUT if the coyotes are far and few between, then move far enough to find more coyotes, hopefully you can look at the terrain and have an idea if it looks good or not. How windy it is also comes into play when deciding how far to move from stand to stand.
It's been said to "mimic a crying baby" with your call. That's a fairly decent dicription. Blow for a 30 sec. to 1 minute series, and sit and watch for a minute or two, or less, or more, and repeat several times until something shows, or until your friend needs a smoke.
Many a veteran coyote caller has had days that they couldn't/didn't call a coyote, no matter how good they are or how hard they tried. Don't be surpirsed if you get skunked your first time out. If your friends can't stick it out any longer than 2 or 3 hours, go with out 'em, take your camara and show'em what they missed.