Really nice implementation by the way.

Re URL length: Yes... I have a feeling it could become an issue. I was wondering if a browser extension might give users the ability to have shorter urls without losing privacy... but haven't looked into it deeply/don't know if it would be possible (browser extensions are decent bridges between the local machine and the browser, so maybe some sort of decryption key could be used to allow for more compressed urls...)

i doubt it would be possible, it boils down to compression problem compressing x amount of content to y bits, since content is unpredictable it cannot be done without having intermediary to store it.