This is impossible to answer without reads on the villain. If he is loose aggro nutcase call... If he is tighter than an 80 year old shortstacking his pension then fold. If unknown I would call and take notes. He could have Kx Ax 33-55 77+. Given he is playing a 3 handed game I would assume he is loose and will be more inclined to take shots at pots.

It's player dependent.

If villain is the sort to float with ace high then betting small for thin value also gives you protection from getting bluffed on the river.

If we check behind on the turn and villain bets it's a bit of a cop out to say we can snap call because he might bluff, as a lot of players at 5nl just won't bluff. They'll also try and check down ace high many times as well.

As played when he makes a pot size bet I would probably make a nitty fold vs an unknown.

Thanks lads!