I need to know how many keys can be pressed down at one time. For instance the logitech g15 can have 6 keys at one time, and the das keyboard2 can have around 12 due to the n rollover.

This is a very important feature that i need to have at least 6 keys pressed at one time because of fps gaming. crouch+move forward+strafe left+jump+quick switch weapon, + one key for good measure.

Does the deck keyboard support n-rollover?

With the exception of the Fire 82, all Deck USB keyboards support 6 keys at the same time. [Once the current stock of the Fire 82 boards is depleted, it will also support 6 simultaneous key presses]

All Deck Legend PS2 boards support unlimited key presses at the same time.

Why would the ps2 allow for more simultaneous keypresses than the usb counterpart? And would the usb>ps2 converter allow for the same results as one that was wired specifically for ps2?

PS/2 allows for more key presses because that is the way the PS/2 spec was written; the USB spec is only written to allow a maximum of 6 plus modifier keys (Alts and Ctrls) for a max of 10 if you want to look at it that way.

Also just FYI PS/2 to USB converters (as well as USB to PS2 converters) will NOT work with Deck products. There are many threads with more details, just in short they will not work.