They can have leave to test those things as long as it's a stealth mission and they can go undetected.
They do, and it is.
If Niko is part of negotiation team, he could have asked the team leader. If not, then he could have if Shepard asked Clara to include it as part of their plan.
They won't start the plan early.
They might be detected the moment they board the ship. It depends on how they do so.

I'm trying to post up the OOC vote notice, so if you can hit me up with your team's plan that'd be awesome! Thank you!