I know that Netflix supports the iPad VGA cable but does it support the component or composite cable too. If an app like YouTube, Photos or Keynote supports video out does it matter which cable I use. I want to connect my iPad to my HDTV and get the best picture possible for Netflix, Photos, etc.

i dont think it matters m8

Yep, all work fine. Netflix looks great on the component cable on my TV.

I have netflix and use the ipad with component cable to stream to my hd tv over the wifi in my house. The picture is sharp enough to watch the movie but certainly not hd quality. But, to answer your question, it works just fine.

This article has some more info:
Six ways to stream Netflix to your HDTV | Home Theater | Playlist | Macworld