Forum:Card trooper and chain Link questions

1 Can I pay the cost for Card Trooper while skill Drain is on the field? How many times can I do it?

2 I summon darius and murmillo at the same time with secutor. I put murmillo on chain link 2 and darius on chain link 1. Murmillo resolves first and chooses to destroy Stardust Dragon, then darius chooses to bring back a Gladiator beast from the grave. Can Stardust dragon choose to negate murmillo's effect? Can D.D. Crow remove the monster Darius summons?