@dodie
I really don't get what you mean with your introduction. If the client thinks that the system implemented was useful and customized to the client's needs, whatever plug-ins you used wouldn't even matter for him. The client decides what works and what is customized not us. I understand how you are the strict teacher type, but not everybody has your brain and simply don't have enough time to do what is needed to be done, so we need all the help we can get. So cut the others some slack, it almost seems you are looking down on most of us.
About your first statement, you did brilliantly with solving her problem so I don't need to help. Also it helped that you guessed that she was using limits in MySQL. Of course, dynamically generated statements will perfectly work fine with whatever database may arise when dealing with pagination.
For the second statement, everyone can and will improve at their own pace.
For the third statement, she may not be as good as the hardcore programmers for now, but surely her overall skills will allow her to be something with more (or less) value. I personally wouldn't want to get stuck programming all my life. The IT industry is boundless. You don't need to be perfectly technical, there is so much you can focus on.