I asked the guys at GS and I was told that everything is possible. It is totally cross-platform and either 32-bit or 64-bit versions van be used to edit the file.
There is one thing to look out for: if someone works on a Project with a 64-bit AC and creates a very big file, when that file is opened in a 32-bit AC it may run out of memory if more than 2GB is needed for the handling of the file.
In that case that user also needs to switch to 64-bit AC.
But this is not very common.
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