do you mean "after" you have topped up? Then yes you use the app to Scan a QR code to pay or at 7-Eleven use the Pay button to allow your QR code to be scanned
It's one original and one copy (or two originals if you're loaded) if you're applying for both licences at the same time. If you intend to return to the Chonburi DLT at another time then you will need two originals.
what's a real tourist? I think the definitions are confusing matters. Just because DTV and Elite Visa holders are holding so-called tourist visas it doesn't make them tourists. As long stay foreigners we saw an opportunity to use a Thai bank account and took it. Now they've changed the rules then that's fine we'll just have to work around it.