According to this Xinhua article, China will be deploying 998, 170 and 887 to Gulf of Aden. It also reports that the flotilla will have more than 1,000 personnel, including Navy special forces troops. We also find out that 998's displacement is 18,500 tonnes in its mission configuration. It should be not a surprise that 998 is going on this mission. China has been sending all of its new naval toys out there. They waited until the LCAC is in service before sending 998 on this mission. The more interesting part are the photos that came out.
First, we have a really nice detailed diagram of 998. It looks like the well deck can only hold one LCAC, but it will also hold a couple of high speed patrol boat. I presume that these will all be used against the pirates. It also looks like the hangar is large enough to hold 4 Z-8s (assuming they do 2 side by side on top of 2 front and back). The Z-8s accompanying 998 were specially fitted with gun pods to assist in attacking pirates.
Here are some photos of the LCAC from the same magazine. Looks like the one traveling to Aden will be 3320. There is also a nice photo of LCAC going at high speed.
A picture of the well deck with patrol boat.
Finally, more pictures of 998 going on this mission.
Anyway, good to see we are finally getting more details on this ship.