Hard case for heavy bashing, the hard case protects the LiPo from impacts and getting flung out of the RC. Soft cases are good for weight saving, so 1/8 or larger RCs need them for weight saving.
It is rated for it, but the Deans connectors have a hard time handling the amps and the connectors can possibly melt. I strongly recommend using XT60 or XT90 as they are much better than Deans.
I don't recommend running Deans with a 3s! I managed to melt a Deans running a cheapo Povway 3s. Something like this should work, I recommend running XT60s or XT90s instead of Deans on 3s or higher.