Rules Questions from Play

[Tywyll]

I was introducing my friends to Melee and Wizard and a couple of situation cropped up we weren't clear on how to resolve by the book. We did out own thing and moved on, but still.

1) When in the Dex order does a character with a ranged weapon shoot at a target that engages them? It simply says 'before' the opponent engages them, but the dex count isn't clear. This became important when a Wizard wanted to Sleep the same figure that was charging their friend. Depending on how you read it, since the wizard and the opponent had the same dex, if the missile user fired as the wizard was casting it would have messed up the sleep spell (waking the target immediately).

2) If you disengage from an opponent who ran their full MA to engage you, do they still get a free swing if their Dex is also higher than yours?