(a) They implemented a very boring transaction/caching/replication layer that is like any other DB except they borrowed the idea that "longest chain" should be used for conflict resolution.
(b) They worked with upstream to get a few patches that were unique to their use-case. Once you're in deep with any DB this really isn't that uncommon.
(c) They used a dedicated (lol non-ephemeral) white-box server that has a lower amortized cost than EC2.
(d) Bedrock isn't bound to the hardware. You could run it on EC2 and reap the benefits just the same except you'd pay more.
