I would put your light on a timer, to prevent any over-growth of anything in the tank.. I think my water got really really cloudy after a few days of leaving the light on 24/7 before

maybe it caused high phosphates in the tank, or something?
As for feeding, depending on how long you'll be gone, it might be better to fast them rather than to try to auto-pilot their feeding regimen. I made the mistake of using a 'weekend-feeder' block for one of my betta tanks once, and it just made the water quality REALLY poor, and I don't even know if my betta could see the microscopic food coming out of it with all the green haze it produced.. Otherwise, since overfeeding is purdy much the #1 way to kill goldfish (I found out the hard way

), if you're going to ask someone else to feed them while you're away, I would make individual baggies of tiny amounts of food, labeled for each day, for that person to feed the babies. Then, HIDE the original container of food to prevent the well-meaning feeder from overfeeding the ever-begging fishies (awww, you're still hungry! here, DUMP!).
I'm not sure about how long you can fast them, though I've heard Toothless™

say that goldies can be fasted safely for up to 1-2 weeks at a time. I'm thinking that you shouldn't practice a fasting regimen like this all the time, but in times of short vacations and obvious constipation, they may be the way to go.
My
Hope this helps!