Just a +1 for browser encryption... you should be able to use pbkdf2 + aes to take an input passphrase with pbkdf2 to generate an aes key to then encrypt an input file in the browser, I'm not sure if you gain much via gzip before/after depending on the document that may already be a zip file (for word/oo, etc).

On the file storage, I generally recommend going straight to a cloud interface to separate storage backend from the actual storage medium... There are self-hosted options for an S3 compatible backend you manage, or you can use actual S3 or one of several other providers for S3 style storage.