Not a direct answer to your question, but I think with your use cases you hit the limit of MS Project. It's a project management tool, but has very very limited task tracking ability.
For your needs you might want to reevaluate what you need from the tool. Maybe a change management system or an agile project tracker is better suited than MS Project. E.g. Trac, JIRA, Mingle, all of them free or cheap enough to try out.
I for example constantly deal with a few bigger (few months) projects and lot of smaller ones (few days upwards) in a small team. I use an agile tracker to do my task management (whast you described you want to do with MS Project), plus collaboration (task management systems usually have good discussion capabilities, comments, attachments, those things).
When it comes to resourcing and other project management things, like scheduling, I switch to MS Project. But I have one single project file there, with a task for each of my projects representing the entire project. So all I need to do is take the time remaining from each of my projects, and can tell when resources get freed up, how a new project impact my team's delivery and so on.