[in each case, the setting for use is directing choir in a public school]

1) I own enough copies of the work for all of my students to use, but I would prefer to make and distribute photocopies to my students. I will destroy all photocopies following the performance.

2) I own one copy of a work which is P.O.P. (permanently out of print) by the publisher. Can I make enough copies for my students to use?

3) Can I borrow the work from another school's library?

4) If a work has recently entered public domain, can I photocopy a published version of the music? (as in, a piece was once published by Carl Fischer, and I bought a single copy from them years ago. The piece recently entered public domain...can I reproduce that single copy I have?

Thanks!!
I should mention, this is in the United States.