Since, to me, it sounds like you are unsure whether you plan to continue or not it would be rather pointless of me to offer any advise/suggestions on how to procede in the future.
With that said, I don't think you made any major mistakes. A few things really popped out at me while reading all of your posts concerning your dwarfs....and yes, there were a few things I would have done different or discouraged you from doing.
Long story short - dwarfs aren't for everyone. They require A LOT of care. Initially, I don't feel your tank was mature enough to handle the bioload of the dwarfs. That combined with the heavy feeding was just something this newly cycled tank could not handle. I never use the "shrimp" method to cycle. IMO, the rotting flesh/carcass of a dead animal combined with all the nasty bacteria it can create is not something I'd like in my water. I'm a strong advocate of using the "pure ammonia" method. (Throw a cocktail shrimp in a glass of water and let it sit for a few days...then look at the water and smell it. 'Nuff said)
I certainly wouldn't consider dwarfs pets that possibly shouldn't be kept. I kept them for 4+ years. My oldest dwarfs were 2+ years in my care. At the time the tank crashed, due to a heater that stuck ON, the youngest dwarfs in the tank were just about a year and the oldest were just about 2 years. So I kept them long-term. It take a lot of time. A lot of patience. A lot of water changes. Again, MUCH more work than the larger horses.
If, after thinking about it for a few more days/weeks, you are of the mind-set you would like to try again, let us all know. We're all here to help. However, if you have doubts or can't be 110% positive you want to continue - I'd suggest you try a tank of something else until that "seahorses itch" returns and you dream of trying it again.
Tom