A plugin (perhaps a collection) with some enhancements to the mark system

What? Summarize the plugin you'd like to see exist. In a few sentences, what's your idea?

Some enhancements to marks I can see being useful to me and others:

1. When I create a mark on a line, leave a visual indication that there is a mark (and possible which mark it is). For example, the line number there could change color depending on the better used or there could be a dot at the end. Ideally, it would visually differentiate between local and global marks.
2. Mark not just a line but a column, too: when a mark is created, its exact position is stored jumping right back there, not just to the beginning of a line.
3. When a mark is created and a mark with the same name already exists, give a warning and ask for confirmation (would need to be optional and disabled by default because I can see this annoying a lot of people.
4. A list of used marks (and possibly their associated line numbers) available for display in the status line.

Why? What should this plugin provide? What problems does it solve?

Marks are awesome but there are a huge brainfuck to use to their fullest and this would fufil part of vim's core use argument of removing mental bandwidth from the user so they can focus on editing.

Potential existing implementations: I have search and am not aware of any implementations that come close to this.

Potential pitfalls: I am not really sure how possible/easy some of these would implement I am not super versed in what plugins can/can't change easily.