a) Perhaps? b) I'll say no, simply because they are not promoting that kind of adition (as of now). Spoiler c) I think the episode will only cover from the inmediate aftermatch of Leviathan fight to Ignis rescueing Noctis, which all will happen on the same day. So I see no room for Ignis to go take a break on a "hub" and do extra quest considering Niflheim is still attacking the city. d) Maybe. e) I don't think so.