@Strawhat:
All VA use Haki. We've four named VA Giants so far: John, Lacroix, Ronse and Saul. The other unnamed Giants are also VA, probably, and they could be an exception, but I doubt John and Saul are. John is special, lol, but Saul is more impressive than the other Giants for picking up a giant battleship and throwing it into a distance.
I guess you're right. I still wouldn't say for sure that they have haki (the marine VA giants), but it's highly possible. John Giant and Saul are special cases yes. I believe they have haki, but as for Lacroix and Ronse, I can't say the same. Especially Ronse; while Lacroix was treated rather unfairly and probably shown weaker than he really is, Ronse was just plain stupid. He's a great fighter, no doubt about that, but he isn't clever. Well, okay, I may have gone too far with the "retardedness"; it can be he just shouted because he wanted to impress everybody around him. Maybe it was a pride thing. Still, I don't think they (Lacroix and Ronse) were promoted to VA because they actually have haki, but because they're giants and they're probably the leaders of the Giant Squad.
As for the Giant Squad, it's unlikely they're VAs. I don't want to underestimate them (I'd be the happiest person on Earth if they kicked some serious ass), but they're probably there for the raw strength and special missions (like let's say, defeating a bunch of giants who are rampaging somewhere etc.).