Does the activation of the plugin change the IDs of the already made orders of my store?
Absolutely not, the plugin will operate only on the orders made after its activation.
Is the numeration progressive? Is it possible to set a certain interval between two different IDs?
The plugin has been conceived to offer sequential order IDs: this means that the IDs will continue progressively in any case.
If I delete an order, will its ID be used again for the next order?
No, the ID will be lost and the new order will use the next number of the sequential numeration.
May there be orders with duplicated IDs?
IDs may be duplicated if you decide to start your numeration with a lesser ID than the one of the last made order. Use prefixes and suffixes to avoid duplicated IDs in your orders.