I need advise how to nurse a damaged bomber back home.

I am looking for Historic and game specific emergency procedures, specially since we have heavy bombers now.

Run a damaged engine and risk fire?. Thrust the fire extinguisher?

How to assert the engine damage?.

There is data about how much can you push a damaged engine based on fuel, oil, boost pressures?.

Thanks.

If there is fire, use the extinguisher. The greatest danger besides fire would be a runaway prop, so feather the prop. The decision of whether or not to run a damaged engine would have to be made on the spot by the pilot, though the flight engineer would help assess the damage.
Was the damage caused by flack, or are there fighters present? Dropping out of formation makes you extremely vulnerable to fighters, so you want to try to stay with your formation, if possible.