Custom House (Crossrail) station

Yes, some closures will be required, but I doubt it will be anything near that amount. If they are maximising the amount of prefabricated construction, then closures of the DLR should only be required to dismantle a few bits of the existing station and erection of the parts that span the DLR tracks.
For the former it looks to me like just the canopy will be removed and replaced with a new concourse, and I suspect much of this could be done with just a station rather than line closure. As for the latter, I'd guess something in the order of just two or three weekend line closures would be required - possibly even just one if they can use the floor of the spanning concourse as protection when constructing everything above that level.