For thing 5, I'm trying Remember the milk. I've added a couple of tasks, deleted one, marked one complete, and added a note. I've poked around in the settings and read some of the help topics, to get a better idea what things the app can do, and how to make it do them. I've enabled tags as a default field, but haven't changed the settings otherwise so far.
It seems like a good tool. There are extra features, like push notifications, that are only available if you upgrade to the pro version, but I think the free version is fine. You can view your tasks in various calendars if you want (Apple calendar, Google calendar, your device's calendar).
It's fairly easy to use. The first screen you see when you open it has a lot of icons that aren't explained, but just going through them and tapping each one reveals their function if the pictures used aren't enough. I like it.