How do I turn a path into a selection in Illustrator?

Convert a Path to a Selection — With a path selected, Command + Return (Mac) | Control + Enter (Win) creates a selection from the path. Note: this shortcut works with any selected path (shape layer, vector mask etc.).

How do you create an object path in Illustrator?

To convert a path into a live shape, select it, and then click Object > Shape > Convert to Shape.