Sorry for the delayed response. I hadn't really looked at that cable before, but the kind of adaptor you need would
probably be this one. Just be careful with the genders and also I imagine it will only supply 5v so only suitable for a 2.5" drive.
I don't have any 2.5" drives in mine so can't see what you are looking at regarding the space.
In theory that would be possible to have all three connected....but why do you need an optical drive? Genuine question, I haven't used one in years and the only reason they are still in my 8300's is that I don't have blanking plates for them! I do have an external USB drive buried in the drawer for the odd occasion.
By far the easiest option for three drives is to have a 2.5" mechanical in the caddy, a mSATA SSD (still quick, just not as quick as it could be) in the mSATA slot and keep the optical. I cannot confirm what speed the SATA slot for the DVD runs at, so it might also be the same as the mSATA slot..in which case you would just get an mSATA to SATA adaptor and not need the adaptor linked above!
For me, I run the mSATA SSD, nothing in the caddy, and the optical drive not used. I get my big files off NAS or internet, and it is mainly an office box.
You can also replace the fan's if you want to make it a bit quieter