I suspect they will port core software running on the cloud first, running C# and chomping tops of RAM and CPU because reasons. Rust helps with both, but it takes time to port. Frontend apps will be the last thing will bring to Rust, maybe using WASM, and to avoid tools, use the same WASM packaged with Chromium for their standalone “apps” and walá: one codebase, all platforms.
Yes and no. They had to put the version identifier somewhere to avoid sorting problems or parsing problems, so I think that putting somewhat in the middle is a good tradeoff.