Sizing pre is good.
Could go a bit smaller on the flop, just set it up so you have a pot size bet for the turn. But ap is also fine smaller just keeps Villians calling range wider
2. 5 is somewhat relevant as he's probably often playing A5s like this and he could play 65s, 54s like this (not saying it's likely). Dead as hell versus that.
3. Checking lets him spaz out with Qx, JJ, TT because he thinks he might need protection.
4. Also lets him spaz out with A2s, A3s, 76s, 87s, some AK.
