M6800 Question - Boot hard drive / ssd questions and more

For anyone who has a 6800, do you know is you can choose to make 'any' of the (4) hard drives the boot drive?

I've got one on order. Planning on putting a 480gb msata drive in, along with a 960gb sata drive in the "secondary" bay, which from the manual, is the harder one to get to (not removable).

I'd like to put a 750gb hard drive in the quick eject bay, for backup or storage.

I have also ordered and received an optical bad hard drive caddy. I took a chance and got the one spec'd for an m6700 - do you think that this one will work?:

2nd HDD /SSD Caddy, DELL M6400, M6500, M4600, M4700, M6600,M6700 [OBHD9-SATA-SATA-B] - $42.00 : NewmodeUS, Hard Drive Caddys for Notebooks

I'd like to use that for additional options, as they arise. Do you know if these can be easily pulled out?? On my m4400, it had a pop-out latch, like the dvd did. With the slot load drive, I suspect things will be a little different?

Appreciate the help!