Digital BW, The Print

I would like to thank Mitch for his tutorial on using Split Channels to convert to B&W.  
This certainly seems to be a very powerful method and one that I intend to use from 
now on.  As I explore this method I would very much appreciate a number of very 
basic pointers.  Mitch has mentioned in a posting here that 5-10% for Blue, 65-80% 
for Red and 90-100% for Green provides him with good initial results.  In his tutorial 
he mentions using Pin light on the Blue channel to provide greater contrast.  I know 
this is a massively broad question but could someone help me along my way by 
telling me what to expect from increasing/decreasing the % of a particular colour 
channel and changing the type of blend mode for a layer.  I know this delves into the 
heart of using PS but I am torn between having to methodically study how to use PS 
better and getting good use out of it now.

Thanks in advance

Steve

PS:  Alan also mentioned copying the Luminosity channel after a conversion to LAB 
colour and using this also.  I assume he meant the Lightness channel.  Any 
suggestions for weighting/inclusion of this also?