As far as i remember YT varies its internal encoder basing on the input video and obviously its compressing your vid again so generally better the input quality better the result.
Here's some more info from their help page, the rest is rather about google, test and trial.
If i understood correctly you viewed the video right after encoding was completed. I remember some time ago when i was uploading the video, after the encoding finished i was only able to view some low res versions. I'm just guessing status is updated based on first resolution is encoded, but other resolutions can be still in the process.
Just wait some time and all available resolutions should be visible.