Pre Order

It’s possible to complete this action from Magento product grid provided you have an option to sort products by category (this feature is missing in Magento out-of-the-box but can be added through customizations or extensions like Extended Product Grid).

In order to set products from a particular category to Pre order, you need to apply a mass action called “Update Attributes”.  On the inventory tab you will need to choose “Allow Pre-Orders” in the backorders field:

Unfortunately, you can’t create such restrictions with this Pre Order extension.

Yes, there is a special column where you can filter pre-orders:

It is a simple product status which is taken into account. This means that the stock status of a configurable product, for example, will depend on the status of the simple product which is currently selected.

At the moment the extension doesn't send back order email notifications when pre-ordered products come back to stock.

No, you can't split an order as the possibility is currently not supported by our Pre Order extension.

The product’s Availability is Out of Stock.

Solution:

1. Turn off the option that automatically enables the Out of Stock status for products that reach a particular quantity limit.
2.  One of possible solutions is to reconfigure preorder settings. For instance, you can enable the preorder option when the product’s quantity reaches a particular limit but still is On Stock.