We are using PayPal for contributing, because it's easier for everyone to make a transaction. We plan to use a Bitcoin Wallet in the future for saving on transaction feeds.
Our PayPal address is : [FILL_PAYPAL_ADDRES]
Botpress is free and open source framework. Our mission it's to create the best bot framework. All the donation will directly go on Botpress development.
If you are interesting to donate for a particular module let us know. We will be very happy to hear your conviction and importance about this module.
Yes, you will receive an invoice by PayPal.