Edit: the chapter was fixed in the meantime. Please to pay attention if you don't understand something. Ask someone at the very least before publishing blatantly wrong translations.
@eh_hk
page 1: She says わらわ which is an archaic way to refer to oneself. So she's just saying "Someone gets a special spot!? Is it me next!?"
You also mistranslated the previous line, it's not that each episode has one person in the spotlight, but rather one person will get a special chapter, just like in volume 1.
You also mistranslated the rest.
"The one in the 2nd volume features someone very popular!"
"Isn't that me!?"
"Whenever I show up there's always a lot of comments on nico nico"
"So it has to be me..."
Page 2: Loli is the character that'll get featured in the extra, but you didn't translate the previous part properly so this punchline makes no sense.
Also you don't get store benefits, you get store specific bonus material.
Finally, the last line was also a reference to the first page, Nega is saying "No, you were already in the extra for volume 1"
書き下ろし means bonus content in this context, you missed this and mistranslated the whole thing.