Concerning the two buff engineer setup. That is actually very common among three engineer ships. I'm 96% every duck ship had that set up, even Squash's galleon as Squash now a days goes engineer on that ship. I remember doing that when I joined the Brood (
for proof go to 55:53 ) and I feel like Smollet I remember Smollet dinkning around with it around the same time. What you will often see is what I call hybriding wherein one engineer is a "pipe buff" which is the common buff engineer with the pipe wrench and a fire tool, and the second buff engineer is a "mallet spanner buff" which is self explanatory.
BFS ran with two of the later on the Kusanagi, only having the one fire extinguisher on my ship. They clearly weren't too worried about fires.
My Junker build has the hybrid setup. I keep the mallet spanner buff, down stairs as it is fairly easy for me to call off my primary engineer to put jump down once out of engagements and end the fires, also it allows for quick rebuilds on my lower deck guns which are generally the more important guns on a Junker. The pipe wrench one stays upstairs as I always want an extinguisher near my balloon and I do help repair and and rebuild the balloon with my own pipe wrench.
This setup allows me to basically have all my engines, balloon, and armor to be pre-buffed and buffed as well as allow for the guns to be pre-buffed, both buffers can help witht he armor so the buff stays up. Basically my ship is stronger, faster, and harder than it has any right to naturally be.