For the first question I deploy him before I use screaming jets when I played today and yesterday, neither of my opponents had a problem with it when I rolled to get a command point back. We agreed that he is on the battle field.
For the second question, I dont know thats a good question. He is not in reserve so I would think he is counted as being on the battlefield. The warlord trait is not an aura ability that affects other units so I would say it works.
15,000 Dark Eldar