Hello Gary,
The logging feature currently is separate from the OpenSprinkler and thus handled externally. I chose to handle it with a PHP script on crontab logging the status. I then parse this log and render a graph for users via the mobile app. As for the firmware side of things, I can’t comment as I only develop the mobile application. As for the host it can be any OS however Windows seems to have the most issues (currently hammering them out). In regard to the log file, if that becomes something stored on the SD card then a simple HTTP request would retrieve it. Additionally, the mobile app would be able to parse it and graph it for you.
I have basic weather checking to activate rain delay if raining however past that I currently do not have plans on making the system more robust (ex: precipitation, etc).
For the backup and import functions on my mobile app, you will notice the button is split. Clicking the longer side saves it to your browser. The smaller button on the right with the icon does actual file export/import.
Hope this helps!
Update: Now that you mention it thought I suppose that export/import situation is a bit misleading. I will see what I can do to improve that.