Does yeast use the salt in the ferment? During the rising process, does the yeast consume and break down any of the salt in the dough, or is the amount you put in at the start the amount you get in your final loafs? (just spotted some recipes I've been usijg have up to 10g of salt per loaf going in!! :s )
Yeast does not eat or use salt.  Salt inhibits or retards the growth of yeast and too much salt can severely impact its ability to leaven or even kill it. ( all though modern commercial yeast is more resilient than naturally cultivated yeasts like in sourdough's ) 

Salt has an effect on gluten, it does not aid in gluten formation but it does ad strength to the gluten after it is developed thereby allow the dough to hold more of the carbon dioxide produced by the yeast. 

Yeast feeds on carbohydrates and sugars to produce carbon dioxide.

We use salt to enhance flavor. 

wikipedia page on yeast

king Arthur page on salt