Q1: If there was no other way to stop the bleeding and the vessel was critical yes. I would ligate the vessel leaving plenty of remnant suture for the attending surgeons to locate the vessel ligated later. This situation would most likely apply to limb injuries and the collateral flow in the limbs are sufficient even if you ligate one major bleeder.

Q2. As I have stated many times before in this forum, NOT if I had a choice. The best option would be for it to be cleaned and dressed and secondary suture done in the ER/MD office where things are more controlled. That being said, if I had to insert a chest tube for a soldier with a tension pneumothorax in the field, I would.