The card only says "while attacking". Does thid mean that you can add a blue die even if you are at long range?

Yes.

EDIT: And then another one with CF, if you want. And yes, you can use Leading Shots at long range.

EDIT 2: But of course, you need to have had an attack to begin with - so you need to roll at least one red before you can add the blue.

I say yes.. .because you are only limited to what colour battery die you put into your pool. Once you've rolled the pool you can add die from other sources which is why some upgrades such as ER say at close range

So how does the order of events work for all of this?

Let's say I have a single red at long range, and QBT equipped. Now normally I would get to roll Red/Blue because of that. But now lets say the attack is obstructed... Do I gather up my dice (red/blue) and remove one, or do I gather my dice (red), remove one so now I'm not attacking, and therefore cannot add the blue one from QBT?

9 minutes ago, Khyros said:

So how does the order of events work for all of this?

Let's say I have a single red at long range, and QBT equipped. Now normally I would get to roll Red/Blue because of that. But now lets say the attack is obstructed... Do I gather up my dice (red/blue) and remove one, or do I gather my dice (red), remove one so now I'm not attacking, and therefore cannot add the blue one from QBT?

You don't get to attack at all.

A lot of the questions here can be answered by a break-down of how the attack sequence works in Armada .

19 minutes ago, Khyros said:

Let's say I have a single red at long range, and QBT equipped. Now normally I would get to roll Red/Blue because of that. But now lets say the attack is obstructed... Do I gather up my dice (red/blue) and remove one, or do I gather my dice (red), remove one so now I'm not attacking, and therefore cannot add the blue one from QBT?

The second (underlined). This situation is exactly why I made the second edit to my previous post.

Effects that add dice to the attack pool* are all resolved after the pool is gathered&rolled. No pool rolled = attack cancelled = no extra dice added.

The extra die from QBT is treated the same as the extra die from CF or, say, Paragon.

*: This is different from cards that modify your battery armament , which let you gather more dice from the start.