Some general answers to your questions, but I'm sure there will be more knowledgeable people than me along in a moment to give you a better idea.
5/16" is the shaft diameter, the spine is something slightly different. The spine is a rating for how much the arrow will flex in flight and will depend on the bow being used. There are various charts around to give you a starting point on what spine to go for.
Left right are pretty much the same, you can use left or right wing feathers but there is little evidence that using one or the other is better for left or right hand shooters. Only real rule on that is using all right or all left wing feathers on the same arrow.
The fletchings can be aligned straight or with a twist, however the need to be spaced accurately and therefore most people (if not all) use a bit of equipment called a fletching jig to handle placing the fletchings in the right place.
As for sites, there are plenty about, Youtube is a good place to start just to get an idea. This for example is a video showing the use of a fletching jig....
http://www.youtube.com/watch?v=pokB6Q_RMFM&feature=related