Will ejected internal HDD really stay ejected until I mount it again? I want to get 2TB HDD in addition to 512GB SDD I have.

I want to be able to "turn off" that drive so that it stays off even after sleep cycles and everything... I'm worried because now when I have an external HDD and I eject it, it wakes up sometimes - for example just by launching Finder which accesses it... not sure, maybe it happens only after I wake computer form sleep, but still... I really don't want such behaviour in an internal HDD. It should stay "dead" until I resurrect it only when needed. Is this possible?

I don't know why is this information so hard to find - nobody reported it, just guesses and partial solutions on forums... So anyone with such setup - can you try?
I suggest to test and use:
    Disk Arbitrator.

This is a small application interfacing the MacOS X disk access interface.
This application may be used in forensic investigation, to protect against unwanted connection of external disks, and to manage very straightforwardly any mounting and eject of internal or external disk
(through the Show Disks Window menu entry).

I wouldn't speak in place of the author, but I can ascertain this tool is working on: Lion, Mountain Lion, Mavericks &amp; Yosemite.

I haven't found any bug in this application, and I would be glad to give the same nul result with many application I have to survive with :(.