Rambling is good! So is personal head-canon! And you make some excellent points. Perhaps the wand Harry used when Snape was teaching him was only for defending himself against Snape's verbal spells and perhaps casting his own to stop Snape entering his mind. Very interesting! And I completely agree about Snape hiding his thoughts in front of Voldemort- he would have to do it wandlessly to be subtle!

Very interesting! Thanks so much for replying.