It is good you will be boarding them 2 weeks is a long time. Depending on the age the food won't be a huge issue BD do go a while some times with out food in the wild. But water would be a issue I wouldn't do more then 4 days and that is with leaving water in the enclosure(but ours normally spill it after a few days)
As for keeping them from getting stressed your best choice would be take their enclosures with them so everything feels normal. They will know a different person is feeding them but that shouldn't stress them too much.