ESP8266 with Arduino Due, i.e. not ESP8266 alone

Hello,
I am working on an Arduino Due in communication with an ESP8266. I made my own code with the hardware serial, but I am still having problems when there's a rare WiFi communication error that I don't know how to reproduce. I am doing a web server for only one client capacity and I need one extra TCP connection for NTP.

Q1Where can I find some drivers already optimized for the Due.

I found this one, although the board list does not have the Due mentioned.

Q2 Is there a certain standard API I should look at if I were to continue developing my own code?

Q3 Is the software here only applicable for an ESP8266 in standalone (no extra microprocessor board)?