@tesmnorth There's no fixed schedule since it's backlogged and being worked on on a best effort basis, so it's sort of hard to tell you exactly how many days. It also depends on how many bugs appear during the integration.
For your first question, it only applies to the hikey board, which has a 4gb and 8gb variant. If you're in a hurry and can get your hands on a hikey board, you can try using it instead since optee + android is supported.
Using a windows/mac is strongly discouraged due to the lack/absence of driver on those OS for the usb connection!! If the host OS cannot 'see' the board, then the guest OS won't either, and you have no way to communicate with the board. A few people managed to get it to work on windows, but mostly not. If you can't get it to work, you might be able to get away with building, but eventually you'll need a linux machine anyway to flash the built images. If that's the only way to go, then try either installing linux as dual boot, or booting linux using a usb drive. At least this is the case for hikey, and probably the same for hikey960 as well.