I've spent a lot of time on the forum, and I believe I got all the most recent official rules about how to evaluate general cover and LOS during a ranged attack, but there's something more specific I can't find any post about, maybe because it's obvious, but it's not for me. So I would love if someone could tell me what are the most recent official rules about it.
I get that when declaring an attack step one is always to check LOS and cover from the attacking Unit's leader perspective. But...

1) Let's suppose the leader has no LOS on any of the desired target unit minis, but all other nonleader minis in the the attacking unit have LOS on all the minis in the desired target unit, the nonleader attacking minis can't still perform the attack because the leader has no LOS?

2) Now let's suppose that the leader has LOS, so I declare the attack on an enemy unit. But I want to use one of my nonleader attacking minis with a different weapon to attack a second target. Can I pick as second target a unit if the attacking unit's leader has no LOS on any of the defending minis, but the second pool attacker has LOS on them?

3) Same as 2, I'm using one nonleader mini for a second target attack pool. The second target unit has no cover from the perspective of the leader of the mini that attacks it, but has cover from the perspective of the only mini that attacks it. Does it get cover or it still counts the leader perspective and it's no cover?

Thanks in advance!

1) The target unit gets heavy cover, but all models with LoS can shoot.

2) See 1)

3) Cover is always determined from unit leader, so no cover.

Will look in rulebook for quotes when I'm not on my phone. Essentially, cover is always from attacking unit leader to target unit, line of sight is model by model. If the Leader doesn't have line of sight, it's automatically heavy cover, and the unit leader can't attack, but other models can.

1) If the unit leader has no line of sight the target gets heavy cover. Models in the firing unit that have line of sight can add their dice to the attack pool.

2) same as 1). You still determine if the target unit has cover from the unit leader. If line of sight is blocked, the target unit gets heavy cover.

3) No cover, though the firing model does need to be able to see at least part of the target unit.

From "additional terrain rules" on page 8:

"Terrain that completely blocks
line of sight always provides heavy cover."

Other than that everything else is based on that while cover is determined from the unit leader, the rules only say that models without line of sight can't add weapons to the attack pool, not that the unit can't attack at all if the unit leader doesn't have line of sight.