I guess the last article I say that OpenBSD have no "handbook", while we could say that this pages can be used as a handbook.
Did you check the release notes about the changes? This guys don't care about compatibility if Security problems are associated. So if you tell me that OpenBSD have some limitations, I need to agree with you, while everything has it's own limitations, If you have hardware issues, that is your problem, not them. Is interesting how features are added and removed, the list of internal features for developers use to build their OpenBSD from Source Code, compiling all.
They have the Ports with the source code, but if you wish to build a single application from source code, you need to build X server.
Build by OpenBSD developers and made for them. Is suggested to use the binary packages since compilation can be tricky, if you don't follow their documentation that describe the process, which include the man pages and their handbook.