1) Yes you can say Allah willed for those events because in reality Allah willed to create a system, and he determined its millions of factors, and he willed to create you and he willed to give you free will and you used your free will, and in then end you came to a specific result. That result was written by Allah (and part of Allah’s decree is for you to have free will). So in the end, whatever happened, Allah knew of it and allowed it to happen.
2) As for what is Qadha’ and Qadar, I recommend seeing this video:
https://youtu.be/m94i4AR95KI