Bear in mind that 1Mb is fairly limited
Rsync file synchronization to ensure it is up to date.
This would very quickly burn through 1Mb
SMS or similar outgoing messages.
Yes, but not arbitrary messages. Just requesting a specific bit of content
Who would support/filter requests for changes in the download content.
I think this has to be a machine/script. The simplest to implement I think would be a Wikipedia search.
So the device can just send email (through a web form) to ‘email@example.com’
With the format:
Language (FR, ES, EN etc)
Search term: XYZ
The script searches wikipedia for XYZ and broadcasts the resulting page (if any)
Bandwidth permitting you could also follow the links and broadcast each of the linked pages.