1) I do not call them back immediately as it is not widespread in our country to leave messages after you were not able to call for someone.
2) I do not send it back because I choose things to spend money on very carefully.
3) Of course I did. As my mother said, you should lend as much money as you are ready to lose and never get them back.
4) I usually feel better because I am relaxed and full of energy to start learning again.
5) I usually remember to give it back and if I don't, they remind me to. The same situation with me lending something to my friends.