Nikonos 5 questions please

Hi

I am about to shoot with the Nikonos V and haven't used it before.
I will be using a Sunpak Marine Auto 3200 flash with it.

In the past I have shot lots of 16mm underwater but not much stills.

Questions
TTL means that if I set the exposure to A and set my apeture, the
flash will expose the correct fill flash, right?
On A, which is apeture priority I gather, how do I know the shutter
speed will be slow enough to cover the flash duration. The bottom of
the frame has a red shutter speed readout. Do I change the apeture so
the shutter speed in within flash sync speed.
What is the flash sync speed - 30th, 60th, 125th?

Thanks for taking the time to read this and for your reply.

If you know of a dedicated Nik V users group I can talk with I will
not have to bother you guys with my petty queries.
Cheers
geoffjak