So for the first post;
Take a look at you manual and see if you have another line out that works for stereo (not surround), I took a quick look at the Creative site, and as usual their help SUCKS !!
According to this picture from NewEgg it isn't clear what your options are;
As for your second question, it doesn't look like you have the usual 2 pin SPDIF connector most audio cards have, the SE is once again Sh1tty edition it seems, and they want you to get a prioprietary connector looking at the same pictures from NewEgg;
http://c1.neweggimages.com/NeweggI [...] 012-03.jpg
I'm not sure if you can get and SPDIF 3.5mm to SPDIF 2 wire connector for that card to plug into your GTX, but that's what the input is for on the graphics card, to allow you to pass audio through the card.
Most motherboard audio and most audio cards have the 2 pin SPDIF connector they refer to like I had on my original Audigy card too.
You may need to send Creative a note to find out what you can so with what looks like a somewhat crippled (by Creative) card.