Arbiter1000:

This is a FAQ for what possibly the Drones would do in Halo Wars.

How Large would a squad be?

I'd say no more than five per squad. 

How would they move in Halo Wars?

For short distances, walking. For long distances, flying. 

How would they react with other Covenant Infantry?

I suppose any other race would see them as useful airborne infantry and technicians, just keep them away from Huragok...

How will they behave?

If left idle, they'll probably just buzz around. During combat, they'd fly around and harass the enemy. 

What weapons would they use?

Plasma pistols, then they can be upgraded to Needlers. 

Would they have special abilities?

Repairing damaged vehicles and/or structures, the limited flying capability. 

Will they have Ranks?

That's up to ES... 

What are they strong against?

Lesser infantry, some minor airborne vehicles. 

Weak against?

Anti-air units. 

How useful would Drones be in Halo Wars?

 As air infantry, they have their uses, like as scouts for recon duties. They are also useful as technicians.