I can't find any recent information regarding weapon ammunition.

The only thing I could find was a 4 years old topic in the archive which implied that different weapons need different ammunitions.

If so, where can I see what needs what ?

Where can I buy ammunition ? I can't see any ammunition category in centerpoint station website.

Where can I find the locations of "Trading Faction owned Commerce Centre, Trading Station or Centrepoint Station" ?

Ammunition was removed from the game years ago, so you no longer need any. Weapons will all work without it.

As to trading faction owned facilities, trading factions will often have lists of those on their websites if they have any with public access. Centrepoint's is listed here.

There is a very handy list of market access locations (Trading Faction owned Commerce Centre, Trading Station) here:
http://www.swcombine.com/forum/thread.php?thread=57383&page=0