Establishing boundaries with other parents

One of my key parenting philosophies is to establish clear boundaries with my children so that they know what is expected of them. I've developed friendships with other parents - and some share my boundaries and some have different expectations of their children. My dilemma is whether or not to share observations of a friend's child with the friend.

Nothing angers a parent more than someone else offering "advice" on how to parent their child. Most of us are not experts in parenting - we're learning as we go. So, my general instinct is not to offer "observations" unless specifically asked.  I wonder if I am respecting boundaries or just staying safe.

Three situations - a mix of real and hypothetical - and I'd love to know if you would tell the parents and risk their anger and potential cutting off the friendship.  Or would you speak directly to the child? Or do nothing?

• You observe their child acting like a bully - verbally or physically - in a repeated way.  Not sadistic, but deliberately nasty with the intent of making another child feel bad. Should you let the children work it out?  Speak to the bully? Speak to the parents?
• You observe their child acting too mature for their age - flirting with adults of the opposite gender to the point of the other adult's discomfort.  Should the adult involved say something?  Should an observer?
• You observe their child cheating - in a game.  Again - should the players work it out?  Should you address the child or address the parents?

And when should you act - in the moment or after reflection?  Or not at all? What is the trigger between letting children work it out and helicopter parenting?

We say it takes a village, but whenever I think of recanting a negative story about a friend's child to the friend, I think deeply about the helpfulness.  Correcting behavior works best (some would say only) immediately folllowing the offense.  The parent may become angry with their child and not be able to effect meaningful change. I wonder if I am really helping the child and parent or just "tattling". What do you do?

For the record, I give any of you the right to call my kids out on an error immediately when it happens and help them choose more appropriate behavior.  Please let me know afterwards.