I also have a question about the print candidates feature within extended print, I printed puzzles out to learn the XY-Wing, but I had to find other techniques first.

How come I have to find other techniques first, when specifying learning within extended print?

When in the GUI, if the user selects the learning feature the puzzle is loaded at the point where that is the only technique that is needed.

It's not the only technique, it is only guaranteed, that it is immediately available. I tested with all prior versions and it worked just fine for me (when choosing learning in extended print, the puzzles are solved up to a point where the specified technique is available). There is a bug though: All cells are always printed black (even the solved cells, that are not givens). I fixed that bug for release 2.3.

If it doesnt work for you could you please post an example?

If a user specifies learning or practicing mode within extended printing, could you allow them to select which technique they would like to learn or practice.

All sections within one print job have to have one single configuration and there is no easy way to change this. If you want to learn/practice several techniques you have to make several print runs.