Sorry that my post was short and not very helpful. I was at work and posted while on break so I could come back later to answer.
To me, your horse has settled in and just like in any herd, they will see if they can move up in the hierarchy. Some will wait longer than others but it will happen.
If this was happening right in the beginning, he could be doing it for lack of respect or from fear. Since it isn't, he's basically telling you off and to back off.
Anytime a horse raises their back leg or backs towards me, I don't hesitate to make the first move and smack them or even kick them. It is really unlikely that we could even come close to hitting them as hard as another horse could kick them. Even if I did kick them, I would do it so the top of my foot is what gets them and not the toe. It would be the same as them doing it to the lead horse of the herd. The lead horse wouldn't hesitate to kick first either.
Pinning of the ears is just another warning or threat the will act if you don't listen, just like raising their back leg. Depending on if the horse is tied or loose, I would do different things. If loose I would make them move and move away from me. If tied, they would likely get a sharp yell at them or a smack. If you do smack them, you do need to be careful to not frighten them or cause fear. That could cause an accident with them or cause their fight mode to kick in because they are trapped by being tied.
It is best to let them be when eating. However, they should still respect you if you are near them while eating. Maybe you could wait to give him feed until you are done near him or wait until he's done before you mess around near him. If he does pin his ears when you are near, he should be corrected though.
Pinned ears or raised leg, this is definitely what I think: Posted via Mobile Device