I don’t think we have a schema versioning available, quick way would be to initialise a vcs in your schema repo which can keep track of all your changes.
Indexing takes time. It will run in the background and you can still query the data untouched by this indexing but it will fail for queries which rely on indexed rpedicates. You can rely on the error message to see why it failed.
If you are changing a schema then the read/write should not happen without the new schema in-place.