@ ynotbrusum – While the lemons provide some sourness the sugar balance it out so I'm not sure if I would count on it for the sour flavor but try it out and let us know how it works.
I highly recommend the souring method in the article. I can turn out a great Berliner Weisse in three weeks if I force carbonate the beer. Just make sure to taste it along the way, the difference between letting it sit for 18 hours is quite different from 24 hours.
@ brewmiser – The recipes make about a pint each and I usually put about one tablespoon of syrup in each glass/bottle of beer. Like all flavorings it's best to start with half of what you think you will need and then add more in small increments till it gets to where you want it.
A liquor shot dispenser would work well at an event if you want to spend a little money. http://www.homewetbar.com/wall-mount-shot-tender-liquor-dispenser-p-1394.html?gclid=CKn2jPjF3LUCFYxDMgod7T8AnQ
Finally, 3 weeks is a conservative estimate, I've kept a few syrups for twice that long without any problems.