Should I power the merchant room

Um...

• After you grab the crystal, the game spawns mobs endlessly (UNLESS you've managed to gather enough dust to power EVERY room then NOTHING ever spawns!).
• Endless points early game where it doesn't spawn the "module killer" crystals and you setup your dungeon with enough turrets. (Points don't really matter but why not? My current run is an Easy Science Pod on floor 6 with 22,000 points. On floor 5 I killed 12,000 monsters just for funsies lol.) You can get away with this even on "Module Killer" floors if you have enough repair, though it's much riskier and requires a lot more attention, of course.
• Most importantly: Endless Food if you can manage the above scenario while also utilizing a character who gets +0.2 Food Per Kill (Soylent Green). Yes that's right get your free, endless food today!
• In addition to food you'll really be min-maxing with free, Endless Industry if you also utilize Recycling in your farming setup. :D
• Since monsters only drop dust if you are lucky and have a Merchant who uses dust for currency you can clear them out of items! This is good to do even if you have full loot on all your characters because you can then sell the extra loot to the merchant on the next floor for bonus materials/dust. :)
• Oh yeah almost forgot there is an Achievement (I play on Xbox One) for surviving IN the exit/elevator for 1 minute. ;)

My current team for this is: Gork (Solyent Green at Level 3), Skroig (SG at Level 3 and SG2 at Level 11), Nanor (SG at Level 7), and Opbot (Recycling at Level 5 and Recycling 2 at Level 12). In the farming room (ideally 5-7 small modules with 2-4 Autodoc, 1 Defense, 1 Tear Gas, 1 Attack) I give Nanor the crystal in floors that need repair, otherwise I have Opbot hold the crystal so every single kill nets food and industry.

Doing this I can achieve hundreds of industry and food each floor. Though some floors just don't work...you absolutely need a single hallway leading from your farming room to your exit, with no monsters spawning on that "side" of your farming room.

Just make sure to have a good exit strategy to get everyone out of the room when you need to, like saving Skroig's Red Plume skill to distract all the enemies at once. :)

Edit: Took a screenshot for y'all. You can see I'm on Floor 9 (on an Easy Armory Pod run) with way more industry than I'll ever be able to use (I still had over 1.5k at the completion of this run despite filling pretty much every room I could with stuff), and my heroes are already way stronger than they should be ehehe. :)

Also I used an additional defense minor module instead of an attack minor module because I was able to fill a number of other rooms with Tactical Huds.

The total amount of a resource generated gets divided between players, rounded up.

Complicating things is the fact that the initial resource yields are not uniform (on an Easy difficulty it's 5 industry, 2 science, 4 food), and the true yield is not displayed anywhere.

Due to this rounding, it is possible to not see any effect from an upgrade, or to maximize your benefit by crossing the "threshold" and squeezing an extra +1 from the system.

In a 3-player game the starting 5 industry per door gets divided 3-ways and rounded up to 2 per player. Starting 2 science is similarly divided into 3 shares and rounded up to 1, while starting 4 food is divided and rounded up to 2.

In such a game, building a first tier generator which adds 3 resources per door opened will give every player +1. Building a single second tier generator produces no improvement over the first tier ones: the total yields would become 5+4=9 for Industry, 2+4=6 for Science and 4+4=8 for Food. However, constructing a second second tier Industry or Science would give each player an effective +2 to the corresponding resource, while a second second tier Food generator would only give +1.

Mechanical pals, multiple generators and Operating further complicate the picture, but the calculations seem to hold: find the actual (hidden) yield, divide, round up or down. This is a chore, but can save one from wasting resources on a useless mechanical pal. And in a roguelike, every last drop counts.