Accepting your challenge regarding the reading order of the Siege and Shadowland Spidey one-shots - I have the Siege: Spider-Man one-shot between issues 2 & 3 of the Siege miniseries, which I have between Amazing Spider-Man 641 and 642 (the end of One Moment in Time and the start of Origin of the Species). I also have Shadowland in this spot, after Siege though, with the Spidey one-shot falling between Shadowland 3 & 4.
I haven’t done the research myself, clearly, so that sounds all right to me, if it works.