Yes. The Kiss of Death rule applies to a model equipped with a Harlequin’s kiss (or Cegorach’s Rose), even if the model is not attacking with that weapon. This means that a Solitaire can attack with their Harlequin’s caress, with +1 Attack for having two close combat weapons, and one of those attacks will have the Kiss of Death rule. Specifically, that attack will be resolved at Strength 6 AP2. If the Wound roll for that attack is a 6, the attack gains the Instant Death special rule. If the Kiss of Death attack is used against a vehicle, it will benefit from the Caress of Death special rule if the To Hit roll is a 6.

In this situation, roll all of your attacks. None of the attacks will miss, and any rolls of 6 benefit from the Caress of Death rule.

If the template or blast marker (before scatter) is placed over any models affected by Veil of Tears, the firing unit is considered to be targeting them, and must roll as described in the Veil of Tears psychic power. If a blast scatters onto a unit affected by Veil of Tears the firing unit is not affected.

No.

No. While Rising Crescendo allows Harlequins to Run and charge in the same turn, it does not specify that this applies even on a turn when they have arrived from Reserves. This means that the usual rule of a unit not being able to charge on the turn it arrives from Reserves still applies.