To select a line at the cursor position, press Ctrl + R.

To duplicate a line, press Ctrl + D.

To delete a line, place the caret at the line you need and press Ctrl + L.

Also, you can Delete to start line Shift+Backspace or Delete to end line Alt + Del.

To move a line up or down, press Ctrl + Shift + Up or Ctrl + Shift + Down.

To increase or decrease intend, select the lines and use Edit | Indent | Increase indent (Alt + Shift + I) or Edit | Indent | Decrease indent (Ctrl + Shift + I) main menu items.