To address the issue of "nagging," and what does/doesn't constitute it... To me, nagging implies that one does not respect someone's competence or responsibility, which is often why it's so irritating (and rude). For example, if I ask my kids to have something cleaned up "before dinnertime at 6pm," I think I would be a nag if, every single hour, I interrupted what they were doing to ask when they were going to get it cleaned up. It clearly implies I don't think they're going to do it on time when the deadline hasn't even been reached. (Granted, young kids might need more reminders about new chores.)
To me, nagging is about ambiguity and frustration and lack of follow-through. The Nagger wants something done, and they have both a deadline and consequences if it doesn't happen in mind; but they don't share this with the Naggee, expecting them to just figure it out. So then the Nagger is hopping around, wanting to know when the chore will get done, and the Naggee is thinking they had plenty of time to do it and it's not that big a deal anyway. And if it never gets done, the Nagger often doesn't follow through with consequences or alternatives, they just get more frustrated.
To me, nagging is one person saying, "Do this, do this, do this--argh! You never do this! Never mind." And the other person is going, "What? I didn't realize it was so urgent or important. And now you're not giving me a chance to fix it, so I'm frustrated, too." Or, "Why should I do it? I know if I put up with four reminders from you, you'll just give up and do it yourself, and not punish me."
But to say, "Please clean this up before dinnertime at 6pm, or you won't get dessert," is not nagging. You (general) say it once, then if it's not done by the deadline, the consequence kicks in--no dessert. Then you say, "If that isn't cleaned up by dinnertime at 6pm tomorrow, the toys will be confiscated for a week." Maybe a reminder the next morning or when the kids get home from school. Then, if it's still not done by the deadline, this next consequence kicks in. After dinner, you have your DH scoop up the toys into a cardboard box and put it away in your closet. Or, if you could just tip a box over and push the toys into it with a broom, your DH could just put it in the closet for you. And it stays there for a week.
To me, this isn't nagging, it's stating expectations plus a deadline and consequences, waiting until the deadline to see if the expectation is met, then following through with the consequences if it isn't. If one kind of consequence--no dessert--doesn't work, try another. And the consequence should never be, "Someone else does the thing instead," unless that consequence feels negative somehow--like hiring a person to do X around the house might motivate a spouse to do X instead, if the spouse doesn't like spending extra money or feels like they're a bad partner if a stranger does it.
These are just my initial thoughts on this subject... I hope they're helpful, and that others will have some ideas as well.