My DS is 8 and was diagnosed with mild ADHD last year. Although we have not had a need for meds, we knew from very early on that there was something a bit different, and I find that's true for most families who have a child diagnosed with this.
Anyway, one thing that was (and still is) great for both of our kids at restaurants is small packs of play-doh. They sell "party-packs" for people to use in goodie bags, and they're just the right size. Just bring a couple along with you and pull them out at restaurants when you need to.
Whenever we go on trips, I make up a small pack for each child with little activities to use at restaurants, the airport, etc. Gel pens (I was afraid that crayons would melt in the Florida heat), stickers, small pads of paper, mini coloring books, and play-doh are standards.
Also, an idea for line waiting...is your DD comfortable wearing headphones? Letting her listen to music while waiting in line might help a lot too. You can get an inexpensive MP3 player and load it up with her favirote kiddie songs. If she doesn't like the ear buds, you should be able to plug in regular headphones into it instead (DS does this with his iPod sometimes).
Finally, as far as discipline, you MUST find something that works for you and your daughter. 1,2,3 is what we've used from the beginning with both children, and it has worked very well for us. All kids need boundaries, and it makes life better for everyone. If you are not sure what to try, there are lots of counselors and therapists out there who can help you. Good luck!