With respect to your #3. This has some connection with a project I've been involved with and which also connects with my #3.
The project seeks to enable students to use their own blogs (e.g. on wordpress.com) as reflective journals. Which I think is a good match between task/goal (reflection etc) and tool (blog).
The loosely coupled aspect enters the picture through the tool we've developed called BAM/BIM.
BIM/BAM essentially provides the administration/management interface teaching staff need to manage and mark student use of the blogs and connect with institutional results processing systems.