1. In my opinion it is abuse usually, the possible exception being in a child who is terminally ill and whose treatment is pointless, painful or distressing and which lessens the quality of life.
2. Giving a child alcohol is not abuse unless it is to excess- we always had wine with meals from a very early age- watered when we were quite little to no ill effect whatsoever.
3. I'm sure it could increase levels of child abuse. I can't imagine many happy abusers, so you have to presume that most people who abuse are tired, stressed, angry and frustrated.
4.Yes I believe they can if they have sufficient concerns.