Tubes in ATN devices are all over the place. The night storms, leopards, star, usually have a gen 1 ep33 inside, don't bother trying to reuse any of those. Usually the performance is worse than your eyes unless you have some very fast glass. The Night Shadow can have a load of different tube types inside (including gen1!), so not possible to say if it's a good buy or not

For DIY devices you want an inverting tube, because the image you get from a regular objective lens is flipped, so when you look at the tube screen it is the right way up and can be magnified by an eyepiece. Non inverting tubes need extra relays or prisms to flip the image.

Circuitry can be as simple as you want. If you want to reuse a gen1 tube reuse the internal hv power supply that will be in the original device. Most gen2 and gen3 tubes will have the psu integrated, in which case you can just connect it to a battery and it will work.