Hello,
You could place a notification when reach stock = 1, so be able to update your stock. You have also to configure and some products in stock. You will be emailed once that the stock is low. Also you could use Inventory to track your stocks.
On your second one you could configure the option you like from the backend under configuration-> Shopfront and under the area Action when a Product is Out of Stock, there you could select what will happen if a product is out of stock, for example you could select Products Out of Stock are orderable, and the field 'Availability' below is displayed. There is nothing deleted or disabled the product, just does not display the product or add some functions, like notify me, do not appear add to cart button, etc..
Regards