Will I get a booking receipt?

Yes, you get one automatically. When you book a flight or add extras to your itinerary/booking, your confirmation email is your receipt/proof of purchase.

As for domestic flights, the fares and fees displayed include VAT at the applicable government rates in the following countries: Italy, Bulgaria, France, Greece, Poland, Portugal, Romania, Spain and Sweden. A VAT receipt will be automatically forwarded by email for domestic flight bookings within these countries.

For Italian domestic flights, invoices, requested during the booking, are sent to customers via Italian SdI system (Sistema di Interscambio).
For international flights, no VAT applies to airfares or fees when travelling on international journeys, however an invoice for an international flight can be requested during the booking.