In addition, I would like to second the inquiry concerning cleaning time. Does cleaning the citadel take 8 days regardless of how many PCs are contributing to the effort? Can the PCs hire people to perform the cleaning for them, and if so, how much does that cost, and how long does it take?
From the core rulebook chapter on GMing:
CooperationMultiple characters can cooperate on the same downtime task. If it’s a simple task that requires just one check, such as a party Subsisting as they await rescue on a desert island, one character rolls the necessary check while everyone else Aids that character. If it’s a complex task, assume all of them are working on different parts of it at one time, so all their efforts count toward its completion. For example, a party might collaborate to build a theater, with one character drawing up architectural plans, one doing manual labor, and one talking to local politicians and guilds.
I think all the cleaning and repairing downtime tasks count as complex tasks, so it takes 8 days if one person does it, but only 4 days if two people do it.
I find it helps to think of "one downtime day" as a spendable resource. If only one PC is "paying" for the cleaning (i.e. doing it all themself) then they have to spend all 8 days. If four PCs all work on it together it only "costs" them 2 downtime days each.