With the Redwood migration accelerator, are custom fields, formula fields, hidden fields, and custom buttons migrated?

And does the use of lists-of-value (LOVs) work with the conditional logic from classic layouts? Sales in the Redwood UX uses the exact same data model as classic Sales, for example, the same tables, including custom fields.

There's nothing special to do for Redwood beyond deciding what to show on the Redwood UI. You don't have to re-set up lookups, formula fields, Groovy object functions, triggers. One exception exists for the triggers work. If you want tab-out-of-fields-like client-side triggers, there's some Visual Builder work for just this type of trigger.

Note: In Redwood pages, there are no custom buttons. Rather, equivalent smart actions are available for you to implement after migration.

To list all hidden fields in Page Composer for migration in Redwood and hide these as well, you'll need to do it manually after migrating the layouts using the migration tool. Redwood uses JavaScript for conditions, and this migration isn't part of the migration tool.