What to ask, and why

Isn't it a conflict if the same company tests and removes mold?
It can be. Many owners hire an independent assessor for pre- or post-remediation testing so results are objective. Ask any remediation contractor whether they are willing to work alongside an independent assessor.
Will the scope keep growing after work starts?
Hidden growth is sometimes found behind finishes, but changes should be documented with photos and readings before more is removed. Ask that any scope change be shown to you first.
Will spores spread through my house during removal?
Containment and HEPA filtration are designed to prevent that. Ask how the work area will be sealed and how air will be managed, especially in homes with multiple HVAC zones.
What stops the mold from coming back?
Fixing the moisture source. Ask for a clear statement of what caused the growth and what repair or ventilation change is needed.
Can work be done while we're traveling?
Often, with a property manager or house staff providing access. Ask how updates and photos will be shared while you're away.