I always use copier paper (Walmart $3.76/ream) in my printer/copier. Copy shops around here charge 10 cents per b&W copy. I can make them cheaper at home. Just remember to print all your foundations at the same time on the same machine. Copiers can vary slightly and this variation can "add" up across a quilt top.
As for needles: I use a 90/14 for virtually all my sewing - quilt block piecing, paper piecing, garment mending. Maybe I'm lazy or not doing something "properly", but this needle works well for me. Some folks have used 80/12 needles. I use what's in my machine and that's a Singer 90/14 needle.
Stitch length is shortened to 1.2 or 1.4. If you find the paper is not tearing easily, just fold it back and forth on the stitched line. This helps "break" the paper fibers and you will find that the paper tears easily. For those pesky tiny pieces that sometimes get left behind, carefully pick them out using a tweezers...or just leave them in. I have started to remove the papers (only in the seams between blocks) before I sew the blocks together. This helps eliminate the tiny, pesky leftover pieces in the seams.
Right way to paper piece? Wrong way to paper piece? If it is working for you...and it sounds like you are doing just fine...don't listen to anyone else, especially someone who is probably trying to sell you something (a different sized needle pack perhaps? Specialized paper?). As others here have said, ask her what her "concern" is.
Hope my comments help.