1) The quick add button is the third from left in the bottom toolbar. The icon is a + sign with some horizontal lines next to it. Click that, then click the search field at the top, then type "Stand", then select "Stand By Me" and it will be added to your set list after the currently selected song and selected.
2) Instead of thinking of this as triggering the auto-scroll function from the recording function, you should think of this as triggering both the auto-scroll function and recording function from a common trigger. On the layout's Edit Details page, you can set both Start/Stop Auto-Scroll and Start/Stop Recording to song selection. Then when you select a song, both functions will start. Or if you want to select a song and view it for a few moments before starting, you can set both actions to Song Second Selection. Then when you select a song, you can get yourself ready, select the same song again and both functions will start. Or you can set them both to Two-Fingered Tap or Three-Fingered Tap. Or if you have a foot switch, you can go to Settings > Remote Control and set them both to the same foot switch message.