I have a VSCode extension that provides a few useful commands. Broadly, they:

1. Register a command for the command palette.
2. On running, record the current file and line selection.
3. Use vscode.window.showInputBox() to get a quick answer from the user.
4. Load some user-configurable settings.
5. Replace the selection recorded in 2 with updated contents.
6. Show various messages throughout.

These are vscode.window.activeTextEditor.document.uri, vscode.window.activeTextEditor.selection, vscode.window.showInformationMessage, vscode.workspace.getConfiguration, vscode.window.showInputBox, vscode.window.showQuickPick, and vscode.window.activeTextEditor.edit.

What are the Eclipse equivalents to these commands? And generally, what is the best source for Eclipse plugin API documentation?