lol I started new game again so I can get ALL collectibles. I think you can have up to collectibles(18, 7, 23, 7, 6) by the time you finish the first mission(Unknown Caller, which is technically the second mission). So that's all the collectibles you can get from the executive sector(not including two areas infested by molds which you can't access yet without dying, and other areas which you can access yet) afaik. p.s. out of those collectibles, you can only get some of them from the very first quest(Welcome to the Oldest House). One called "Visitor Evaluations" under Correspondence is bit tricky to get.