Just started with it, myself, so I don't know how helpful my answers will be beyond for the first question of why I decided to. That was because I fell in love with silkied Cochin bantams years and years ago, finally got my hands on just a few of them, and then for many years could find
no one else with them to try to get any more of them. When I
finally found someone to get more birds from, I decided I never again wanted to have that feeling of watching my birds grow old and die off while wondering if they could be the very last of the variety, or have to scramble to decide what outcrosses I could make with what I had available to me to keep them going while my birds were still young enough to reproduce. So the obvious thing to do was to get serious about preserving them while I had the opportunity to get more of them. There are several silkied varieties of other breeds that I'd like to do the same with if I can ever get my hands on them as well. The silkied varieties that pop up in random breeds every now and then are terribly underappreciated and unfortunately often disappear into obscurity as a result. I love silkied feathering and I want to make any effort I can toward preserving silkied varieties of breeds as much as I can.
As for the rest, I can only answer with what I plan to do as this is my first year actively being a 'chicken breeder'. I plan to hatch around 100 chicks this year, and I expect to keep maybe the 10 best out of them. If all goes well, next year I'll aim a little higher, but this is my first go at it and I don't want to overwhelm myself early on. Ones that don't make the cut I'll sell with full disclosure, and put that money toward feed and upkeep for the ones I do keep. I don't have any intention to show my birds at any point, though, so I can't really answer your questions about that.
I at one point had what sounds like the same point of view as you, that breeding chickens was something that sounded interesting and like it could be fun, but not something I was sure I could really do let alone be willing to commit to doing, and before the silkied Cochins all the breeds I liked were readily available anyway so I had no reason to try. I guess it just takes finding the right breed and a compelling reason to dedicate yourself to that breed.

The hard part for me is knowing I can't keep them all. The chicks I'm hatching, I just don't have the room for them all as adults. The adults I've raised and gotten to know, some will have to move on as younger birds come in to take their place in my flocks. It's tough, but I want to see this variety thrive, and part of that is not just breeding the birds, but also getting them out there for others to gain interest in and maybe even fall in love with as well.