My husband had his gall bladder out when our oldest was about 8 months old, and was back to working two days later. It really wasn't that bad, as far as surgeries go...
I will tell you that if you have been told that you should have it out, it's a good idea to go ahead and do it. Both my hubby and his mom were told that they needed to have it out, then put it off and ended up having it done unexpectedly when the next attack came. It's not a huge surgery or anything, but with kids it's always nicer if you can plan ahead.
Don't worry about your daughter, she'll do fine. She's old enough to empathize that you're in pain, and sell it to her ahead of time as, "This means that Mommy will have several days to cuddle in bed with you and watch cartoons/read/play games". Keep in mind that while you're recovering, you'll actually have more time with her than you normally do, if your busy life is like the rest of us :) I had a shoulder reconstruction surgery when my older one was 4 1/2 and younger one was 18 months (both total mama's boys), and I couldn't believe how well they did. Even the young one was super careful around me and so affectionate and loving and as "helpful" as he could possibly be (sometimes a little too helpful, LOL). Your daughter is old enough to actually help you out a little, though... The biggest thing will probably be her worrying about you, so just make sure to talk with her about it ahead of time and explain things like, you'll be really sleepy after the surgery, you won't be able to lift her, etc.
Good luck!