To answer your questions individually:
Tipping should be between 15 and 20 percent, especially if you have your food delivered. Not tipping a delivery guy/gal is a guaranteed way to make your service for the next time you order worse. Honestly, we keep notes on this in our computer. I’m not joking. @adreamofautumn also makes good points about people who sit around for a long time; we don’t mind, but make sure you’re aware that you are possibly keeping us from getting another table (and therefore another tip) or from getting off work. And I’ll reiterate the busser/runner point, and add that the same is true of bartenders. Take those people into account when you are ordering drinks from the bar or when you have a busboy. @Marina is right as well, though – if the service is terrible, it isn’t necessary to tip well. The promise of a tip is what ensures that service will be pleasant, timely, and correct. As a waitress, I tip really, really well when I get good service, but I also tip terribly when I know the service could have been better.
At my waitressing job, it was annoying when people made it an even amount, because we waitresses didn’t get any of the silver change, only the whole dollar. If the tip was 2.99, we only got 2.00, the extra 0.99 went to the manager. If the manager was really nice, he would cash out all the change and split it evenly amongst all of us, but he was under no obligation to do so. I don’t think that’s typical of restaurants necessarily, so I guess if it’s between tipping 5.00 and 5.37, for the most part, the extra 0.37 cents isn’t terrible.
I didn’t mind when people asked for refills, as long as it wasn’t when I had food in my hands or when it was obvious that I was busy with something else. It can make things easier when people ask, because I don’t have to go around and check, but it also could stress me out when I have a few things that I’m doing already. I would rather someone politely ask if I’m not incredibly involved with something else already.
I don’t feel cheated if someone only orders water, mainly because I’m a college student, and I understand that saving that extra 1.50 on a Pepsi can help. We were supposed to charge 0.25 for water at my restaurant, and when people were particularly nice to me, I didn’t bother charging them. I did get annoyed when people would complain about the charge for water (I didn’t make the rules, surprisingly) and when people would wait until after I put in an order to ask for it to try to avoid the charge.
Other things that I think would be helpful to note:
Make sure that any kids you have with you aren’t rowdy. The worst thing at my job would be when a table of 8 kids and 3 adults would come in, and the adults wouldn’t pay any attention to the kids, who were screaming and getting shit everywhere and being an overall disturbance. When I was a kid, if I was making a fuss in a restaurant, my parents would threaten to take me out if I couldn’t behave. No wait staff wants to deal with your misbehaving kids. Kids are some of the worst people to have to serve, no lie.
As a general rule, if there is a trashcan in a restaurant (especially the kind where you order at a counter and sit down to eat), regardless of whether your food is packaged to go or not, you should throw away your own trash. Even if food is brought to your table, if there is a trashcan in the seating area, that is an indication that you are to deal with your own trash. And if you don’t want to, you best leave a few extra dollars for whoever has to.
If you insist on sending back food, be courteous about it, even if you’re angry. If you yell or berate or insult the wait staff or make a scene, you’re creating a bigger headache for everyone. If your waiter/waitress is being absolutely unreasonable, rude, unprofessional, or uncooperative, calmly ask to see the manager. There are better ways of dealing with an issue than getting in a fight with the waitress. You’re also less likely to have someone fuck with your food. (I, personally, never fucked with anyone’s food, but I have seen it happen before, and you really want to avoid that, if at all possible.)
Understand that not everything is the waitress’ fault. We don’t set the prices, we don’t have the power to control how big our rush is, we don’t cook and assemble everything you order, so we very well may not know that the line chef forgot to leave mayo off of your sandwich. Bear with us, sometimes. Waitresses will forget things, we’re not perfect, and if we apologize, please understand that we’re doing our best. Some waitresses don’t care, but some of us are earnestly not at fault or sorry.
“Please” and ‘Thank you” are great as well. If you are nice to us, that makes us want to serve you better that much more.
Also: the only time I have ever had a waitress sit down at my table was when I was at Hooters (not by choice, I’ll have you know!). I’m pretty sure that that is generally encouraged there, however…