Are you asking if the CLK output can be programmed to generate different output frequencies or if the pin can be programmed to function as a GPIO? Answering the GPIO question, you only can switch them one at a time.
Regarding the last question, we are in the process of making more documentation public so I'd suggest you to keep checking the documents frequently. Please be patient.
I'm asking of programming the clkout to another frequency, such as 25MHz.
Typically such a clock is part of a programmable clksybsystem with predevider or postdivider of a pll. The frequency is quite untypical, so i guess it's not needed to be 19.2 MHz for other sybsystems on the chip.
At the moment i think about adding a USB to Ethernet port that could benefit of a 25MHz clock.
Concerning the IO-Ports i guess they are arranged in IO-Ports and maybe are switchable in groups - even if it's not provided by Intel at the moment.