To date, no game updates have modified the FW. Mostly add-ons and bug fixes that are downloaded to the HDD. If $ony starts sneaking FW updates in to game content downloads, I'm sure you will find that info in our front page news posts.
Can we download the game patches on PC then use the Proxy to upload on the PS3 via FW Bypass?
Probably. But it would be eaiser using the FW check bypass decribed in another thread on this forum to just download directly from PS store onto your PS3. I can confirm it works fine bypassing the 1.6 check with 1.54 installed on the console.