Github repos need git to access them. Github has a crapton of help. Or you can just view them through the browser if you want to simply reference them...
Bukkit does require a "bukkit" version be generated- this is mostly a matter of converting the MCP based API to the bukkit based one. There are a variety of solutions to this and it's an active area of research at the minute- for now, assume that once you've built your mcp based SMP version, there will be a way to create a bukkit version from it. I will refer you to mcportcentral.co.za for examples from other mods that do this right now, though the process there is a little bit clunky at times
On your last question there is no information that I have seen at all. I believe there's "hidden" work on the API going on, but that the 1.3 changes are so that the API (which is likely 1.4) can be SMP only...