The workstation is not connected to the codebase via SSH on a server, but rather the version control clients are remote and mapped into the local filesystem via FUSE. So the workstation is less of a dumb terminal; programs that access the code can run locally, even though the code itself is not stored locally. Therefore, version control clients can be accessed with various web-based tools as well.
Not all developers used a workflow that includes Piper/CitC, but most do. From my limited view, the Piper/CitC workflows were the most painless.
Debugging - I only ever used a debugger for Python, and in those cases the application I was running was local. Otherwise I never used a debugger but rather logging (printf debugging, essentially). I'm of the opinion that if you have to open a debugger to understand the code, you've already lost. Others might have better stories.
Remote machine - as mentioned above, there is no remote machine. Things are done on your workstation. The build commmands can build things locally (slow) or farm them out to a cluster of build machines in datacenters (fast). See https://bazel.build/faq.html#does-bazel-require-a-build-clus...