Basic question about Nodes

This is in reference to cycles, but also a general question.

Is it O.K. to use two instances of the same input node? Say RGB or Texture Coordinates. How about Image Texture nodes? Is a single input used twice, in it’s entirety, when connected to two different things anyways?

Really want to clean up the node editor view, it honestly looks like it’s been visited by spiders; however really wouldn’t want to change it if it impacted anything in a noticeable way.

Is it O.K. to use two instances of the same input node? Say RGB or Texture Coordinates. How about Image Texture nodes? Is a single input used twice, in it’s entirety, when connected to two different things anyways?

You can add two instances of a node or just connect the one node to multiple other nodes

Really want to clean up the node editor view, it honestly looks like it’s been visited by spiders; however really wouldn’t want to change it if it impacted anything in a noticeable way.
Add nodes systems into a group (Ctrl+G) or organise with a frame node which you can name and colour
http://wiki.blender.org/index.php/User:Phonybone/NodesPatch_2_60#Frames

That didn’t really clarify it for me. Is two instances of the same input or image texture nodes is the same as one fed into two nodes. Is the same texture “used” only once regardless of the number of image texture nodes or is it loaded once per node? Is one way of doing it “lighter” than the other?

Both ways are identical. The user of the image datablock is the material, not the node. You can test this for yourself by opening the image in a UV/Image editor and watching to see if the number of users on the image changes whether you have multiple node instances or a single one. If the image is only being used by that one material the number will always remain 2: the material and the UV/Image Editor are the two users.