Fast Align requires two separate islands and does not work within a single island. However, Align (step-by-step mode) can be used within the same island. You can align one vertex (or a selection of vertices) to another vertex, while preserving their relative positions.

Smart Align attempts to find the shortest valid transformation between source and target. It minimizes both translation and rotation, aiming for the most direct and predictable alignment result.

No, rotation and flip are not supported in vertex mode.

Yes, Fine Tune allows rotation using a visual gizmo with snapping and manual angle input.

Yes, in Align mode you can select and move multiple islands together.

Select a matching pair of elements (vertex, edge, or face) and run Fast Align to snap the entire island to the target.

Vertex, edge, and face selections are supported.

No, Smart Align works in Edit Mode only currently.