How is a Civilian Expert treated by Military?

You will be given the rights and privileges of not being in military however as far as command goes your in thier world and you follow thier rules unless you get a DOD pay grade.

If he's put in charge of the group he's working with then yes he would be in control.

Every time a new submarine is commissioned in the Navy . Civilians ride the boats on the shake down crews to evaluate the performances. Nornmally the crew and civilians work side by side.

It would be like ordinary work. They are not anymore skilled than him just because they are in the military.

Civilians working with the military will find themselves treated with the utmost respect and deference. If they are total jerks or whiny, the respect might become thin, but it will still be shown. That's how military members are brought up from the time they are recruits. Civilian experts are normally only in an advisory role when it comes to patrols and convoys. They may be allowed to give instructions if they are in a training role. Those aren't really "orders" exactly and it's not like they would be participating in the operations themselves. They might walk or run along beside or behind them to continue giving guidance, but they wouldn't take the role of commander or anything like that. A guide would be listened to if the person commanding the patrol told the rest of the soldiers to listen. Civilians can be in charge of military members in some support roles, such as in procurement, logistics, and maintenance. In that case, they are normally Department of Defense employees with clear roles as laid down by regulation. No idea how it works in other countries.

Civilian technical representatives (TechReps) are treated as respected colleagues if they know their stuff and know how to relate to the service members. I was lucky to fly an aircraft built by a privately held company, so they had tech reps that had worked for the company for 30 years; they had an amazing rapport with both the officers and sailors and we all listened and heeded anything they had to say. If tech reps are pompous asses or do not really know as much as they think they know, they are treated as excess baggage--they are politely ignored. They cannot ever issue commands but if they have earned the respect of the troops, the troops will be pretty darn quick to follow their suggestions or recommendations. Civilian contractor intel folks would not be in charge of service members. The only way civilians can be in charge of military personnel is if they are Government employees in a clearly defined command structure that places service members in billets that are subordinate to them.