Evade on a squadron seems an interesting choice. I have no idea if it will be any good in game, but I love the mechanics of Swivel-Mount Batteries (also "focus" tokens - what is this, X-Wing?). Slightly curious how those Hyperspace Rings actually fit onto the V-19s...

Both removing a dice for obstruction and removing dice for Jamming Barrier happen "before" rolling dice: Obstruction: "...the attacker must choose and remove one die from his attack pool before he rolls dice during the “Roll Attack Dice” step." Jamming Barrier: "... the attacker must choose and remove half of the dice from the attack pool, rounded down, before rolling." Then we go to the Effect Use and Timing part of the rules, which says: Effect Use and Timing: "... If two or more of a player’s effects have the same timing, that player can resolve those effects in any order." So the attacker gets to choose which order to do these in. If there is an odd number of dice in the attack pool it does not make any difference, if there is an even number, the attacker wants to remove the obstruction dice first.