Great questions raised here. Let me try give some insight:
1) Can you use a visa debit to buy bitcoins online? If not from coinsbank, is there anywhere else?
I've written up a full explanation showing how it is possible to use a visa debit or mastercard to buy bitcoins:
https://howtobuybitcoin.io/#Which_is_the_best_payment_method_to_get_bitcoins . You will aslo see that one can buy btc with cash, paypal, and banktransfer (the cheapest but slowest method).
I know that is not a popular method but in some places, especially in big cities, there is the option of crypto ATMs. Currently there about 1170 machines as this site claims
here. Eventhough is an expensive way in some places but some of these machines has the nice feature not only to buy but you can sell to fiat too. So for the sake of completeness of your guide, which IMO it is very well written you could add this option too.