Can you educate me on small cameras?

I've always been a big camera person. Mamiya TLR, then RZ67. 4x5 monorail then 8x10 flatbed. My smallest camera currently is a Nikon D810 with grip and a bag of lenses. However, I'm starting to run into an increasing number of days where I really don't want to go through the effort of lugging the D810 around yet the camera in my iPhone doesn't really cut it, mostly due to the single, too wide, lens. I'm thinking more and more about getting some sort of small camera to fill the gap. Here's what I'm looking for, as far as I know, but if you guys want to point out things I'm missing, I'd love to hear it.

1) Able to be operated with big hands/fingers
2) Aperture and shutter speed MUST have separate controls on the outside of the camera, I would prefer that ISO and white balance can also be easily adjusted on the outside of the camera (I can get through a normal shooting day without using menus and without having to do the "hold this, while spinning that" dance, in other words)
3) Available as body and at least one lens (prime is fine) for under $400 used.
4) Flash hotshoe on the top so I can mount a radio trigger
5) Small enough to fit into an oversized pocket. My jackets have big pockets, so I don't need to be Yashica T2 small, but it can't be as big as a D70 was either.
6) Shoots raw
7) Bonus points if it takes CF (though I suspect that's a pipe dream).

What systems should I be looking at to fit those needs?

Your Nikon D810 is the largest of the 'small camera' genre. The smaller format sizes are smaller in overall camera size (and uses of shorter FL to achieve same AOV, with accompanying reduction of size and weight of lens). In declining order of format size...

• FF
  
• APS-C
  
• 4/3
  
• P&S sensor size
  
• Smartphone
  

"Manufacturers list sensor sizes for DSLR and point-and-shoots differently. DSLR sensors are measured in width and height in millimeters, but point-and-shoot sensors are measured diagonally in fractions of an inch. For example, Nikon lists the sensor size of its Coolpix S3200 as 1/2.3 inches, while Sony lists its a99 DSLR’s sensor as 35.8 x 23.9mm. To compare the sensor size equally, you can convert either measurement into an approximate measurement in diagonal inches. In the two models mentioned, the Nikon sensor is approximately 0.43 inches and the Sony’s is 1.69 inches. As you can see, the Sony’s sensor is nearly 4x the size, which will produce image quality that’s much better. Sensor-Size offers a handy calculator that does the conversion for you. The site also lists the specs of some of the most popular models."
http://www6.sensor-size.com …60&kw=camera&sh​owDomain=1

The generality is that the larger the individual picture, the more freedom from noise in very low light. So while you can get light and compact, it usually is accompanied by noisier pictures at low light level; in good light you might never see a difference. So, depending upon your shooting situations and your own tolerance of noise (lots of novices mistakenly call it 'grainy'!) that determines how small is acceptable to you.

And then as to packaging size...there is a 'bridge camera' which has a somewhat small sensor, yet it comes in a rather bulky external package, like the Nikon Coolpix P1000, which is large due to the convenience of not needing to change lenses. Where the P&S is designed to be usually small and slim, the bridge is designed to be usually bulky.

If you want a small interchangeable lens system, then considering a m4/3 or APS system are the main conteneders. The Sony A6000 series gets good reviews. If your budget for body and lens is $400, than your options are older cameras. A Sony A6000 with kit lens just fits your budget.

Sony Alpha A6000 24.3MP Digital Camera with 16-50mm Lens

Canon G7 X Mark IIBEST BUDGEt: Versatile Zoom Range Robust Body Good in LowLight Great Image Quality, best camera.

williaty wrote in post #19027379
1) Able to be operated with big hands/fingers
2) Aperture and shutter speed MUST have separate controls on the outside of the camera, I would prefer that ISO and white balance can also be easily adjusted on the outside of the camera (I can get through a normal shooting day without using menus and without having to do the "hold this, while spinning that" dance, in other words)
3) Available as body and at least one lens (prime is fine) for under $400 used.
4) Flash hotshoe on the top so I can mount a radio trigger
5) Small enough to fit into an oversized pocket. My jackets have big pockets, so I don't need to be Yashica T2 small, but it can't be as big as a D70 was either.
6) Shoots raw
7) Bonus points if it takes CF (though I suspect that's a pipe dream).

EOS M6 with a 15-45mm covers all your stated except #7 unless you're being picky with the AWB. Do you want/need a viewfinder?
The lens has a funny slide control to allow it to park with lens at minimum length which I find annoying.

Given that one of your criteria is that is must fit in an (oversized) pocket, I think that rules out all interchangeable lens cameras, doesn't it? Unless by 'oversized pocket' you mean something like the huge things we see on cargo pants?

Huge like on cargo pants, yes. Most of my coats have pockets big enough I can get the smallest Nikon DSLRs with a kit lens into them.

The EOS M50 with the kit lens has often popped up on Canon's Refurbished sales for $360 before tax. Absolutely tiny to me, I'd imagine most Micro 4/3 cameras to be even smaller though.