These are really quite interesting multi-role ship. Most often seen in the following roles.
Most often seen hanging around providing mining boosts to a mining fleet in systems. Can also be seen in a mining fleet that is stripping a belt, using its various holds to store the ore so that trips back are less frequent. Often attended by a Miasmos or two to ferry the ore away. A Miasmos however has roughly the same ore storage capacity as an Orca, so why both? Not sure but its there.
Its lost and going to be shot shortly.
To be honest its not really a ship for low sec. If it does jump in, fit properly it should have enough time to get back to gate and jump out. The truly mad could use for mining boosts, but with little organised mining, why bother.
Usually sitting at a POS in a bubbled system providing mining bonus to the fleet of care bears that are currently mining. Been there done that, always an Orca, always in/near a POS or on the station undock.
Usually built in place or ferried in via a direct wormhole.
In any hole it can be used as both a Corporate hanger Array, Ship Maintenance Array and Ore Storage that does not go offline if the POS is reinforced. So its all accessible, and uses no power or cpu on the POS so the POS can run more weapons or modules.
If present it has to be built there and cannot use a hole going out. So its stuck. Other than Mining bonus and storage, That's it.
C2-C3-C4 Can use the holes in and out. Most common use would be to "role the hole". This is to either get away from a hostile or potentially hostile connection, or to get away from a boring one that offers no targets of either the sleeper or player kind.
C5 -C6. You have, or should have capitals for hole control, but the Orca would have its place as a less massive weight to throw around.
How to tank an Orca? Well with the Kronos release you would now be mad to do anything but hull tank. That's right. To be fair even before, hull tanking an Orca was not a bad idea.
Base Shield : 10,750
Base Armour : 6,900
Base Hull : 46,000
With 2 Medium and 4 low slots, Idea for 3 new hull rigs and a Damage Control.
With Trimark Armour rigs and a DCU II the EHP is a staggering 284,000 HP
With Transverse Bulkhead rigs and a DCU II it goes up to a whopping 346,000 HP
I can see ganks on these being reduced as with a normal armour tank you would still want to use something like 3-4 Brutix to stand a chance. With the hull rigs it becomes a lot less ISK efficient to use anything to kill them.
Sorry this has been disjointed, written over a week.
Now if anyone can tell me other uses for an Orca, let me know, as I am skilling up for one for use in a wormhole.