Some queries regarding My Cloud 3TB

I recently bought my cloud 3TB ver. with firmware v04.01.04-422 installed.
Should I upgrade to the latest firmware or downgrade to previous ones, as I need my NAS to be stable?
Also can I install transmission or other bt client on it?
What other info or mods to get the best performance?
If it crashes, are there 3TB images available to bring it back ?

A search of the forum using the search option (magnifying glass icon) yields answers to all your questions.