Idle power-draw sitting at 3.5W and actively reading at 4.7W and actively-writing at 5.1W. This is for just 1 3.5" disk connected. It will be less for a 2.5" disk.
No, and it can get a bit hot. I have used it in a cabinet which was ventilation cooled. If anyone finds a mod where a fan can be added, let me know I can 3-d print it for extra cost obviously. One good thing is that it spins down the hard drives, thus saving on power and also giving a chance for HDDs to cool. It works perfectly with SSDs though 
This would be a concern for everything possible in the world . I mean what if my UPS malfunctions and destroys my SMPS. What if my SMPS malfunctions and it destroys motherboard, cpu, ram and hard drives. But yes, valid concern, I mean the house can catch fire and the precious hard drives can be ruined too.
That being said for in last 9 years, I have used it in 2 ways -
- I would use it as my in-house monthly backup for all my VMs. I would load hard drives, connect it to my PC, run my backup routines and it would take/sync backup overnight and I disconnect in morning.
- Later, after I moved to India, I had to sell my storage server in US, I temporarily used it as USB NAS for around a year after I finally found a Cooler Master Cosmos SE 2 -Cabinet to hold 12 hard drives - #16 by nik1234