Q:
Living World S2
A:
You would need the more recent achievements if you want the Luminescent version of Carapace armor, as you get ascended trinkets needed for the collection only via achievements. You should be able to get all the Carapace armor from the Silverwastes vendors, for 1000 crests each; doing the story gets you quite a few of those pieces just by sending alts through the story. (Note: the Carapace chest piece only comes from fighting the Vinewrath in Silverwastes, and it is RNG each time whether you get the boxes you need after the first one).
Also some of the earlier chapters give you items needed for the Mawdrey backpiece that eats Bloodstone Dust, though I’ve heard they are also available for laurels, maybe?
You’ll miss a lot of story, of course, and achievement points from the achieves even on the chapters that predate Carapace.
Q.Q How long does it usually take per story? 1-2-3hours?
That depends on how proficient you are at combat and dodging, and how much you want to see all the extra bits (in one chapter you get into a large library jam packed with readable books, as well as plenty of random scattered artifacts to examine).
On one chapter’s end fight I was at it for close to an hour, armor completely broken, screaming at the boss (and I am normally a very calm person). But going back with two alts, I managed that fight much more quickly.
Generally it will go faster in a party. Are you on NA? I’m generally available mid-afternoons eastern time if you want a guide. If you just want the unlocks and don’t care to savor the extras, I can zip you through fairly fast with a few explanations of mechanics and my added firepower.