Using an External Amp with a Xonar Essence and Volume Levels

Hi there, I have been reading head-fi for a while now, but have just decided to make an account because after reading about this through many threads, I am still confused.

I use my computer as my source for all my listening. Currently I have a Asus Xonar Essence ST with my DT880/32ohm (I didn't think I was ever going to buy an amp which is why I went for the 32ohm version.. oops!) connected directly to it using the Line Out. The issue is, I am going to be ordering a Schiit Lyr Amp (and some LCD-2's, but that doesn't matter for this) soon and I'm not exactly sure what to connect it to on the soundcard's outputs. I read in another thread that if I use the RCA outputs on the soundcard that this will bypass the Amp portion of the soundcard while leaving the DAC to do it's job. Is this true? Is this the best way to go about it for optimal sound quality, or is there something else I should be doing? Also, when I eventually get an external DAC as well, how do I use my Xonar Essence as strictly a transport (not utilizing the DAC or AMP portions)?

The second (and somewhat related) question is, what volume controls should I use? I know already that Winamp should be at 100% volume, but what about windows volume/sound card volume? (The Xonar Audio Center that comes with the sound card moves the windows volume slider when I use it as well, why is this?). If I am using the sound card as strictly a DAC and using an external amplifier, should my windows volume be maxed and my amp's volume control be used? What about when I upgrade to an external DAC, how would the volume controls look then?

Sorry about the millions of questions, but I am truly excited about getting deeper into the high end audio world and would greatly appreciate any help anyone could provide! 

I know it's a lot of questions, but I'd really appreciate an answer if possible.

Anyone?

Mad Max, thank you very much for you response, its very appreciated. I was actually looking into using ASIO/WASAPI or something to that effect already, I will research it more when I am home. I had reposted this thread to the headphone forum, because I was getting a lack of responses, but if you look at that thread (linked below) they are saying to leave my windows/soundcard sound at 50%, while you are saying to max it out. From what I've read, you are supposed to max it out like you say, but some people say there is distortion if you do that, do you have any other insights into this? You can reply here or the other thread.

http://www.head-fi.org/forum/thread/542257/using-an-external-amp-with-xonar-essence-st-and-volume-levels-noobie-questions

Again, thank you very much!