Ask all you want and need, just don’t always expect a response. Even I don’t always get a response (ref) but I know it is nothing personal and if I dig into it and have another question it might get answered. And as you have noticed, asking twice is fine.
Bratko would be my first choice for teaching as it stays closer to practical problems. Be aware that conc/3 in the book is really append/3. Sometimes the books version of conc/3 will cause a problem while uswing SWI-Prolog append/3 will work better.
Pereira/Shieber is a nice follow-up to Bratko because it goes more into theory and dives deep into some topics.
Clocksin and Mellsih is widely referenced but not my first choice on the list.
O`Keefe could be considered an exegesis of Prolog if there were one. It is the most advanced of the four and not really a first book. It is also my first choice now that I know enough to understand Prolog as it gives insight into writing excellent Prolog code.