I hear warehouse can be soloed by certain builds, but I am not sure of the specifics there.
General tactics apply vs these NPCs though, use your team's skills as you normally would (I.E. Have your "tank" initiate the fight vs the NPCs with a single shot or burst, then have him apply superstims while your teammates cover, or have him run back while teammates cover etc). 2-4 seems to be efficient numbers for clearing reno, unless you are expecting a big fight etc, double that to 4-8 for warehouse.