What are the differences between baking in bulk and baking in smaller amounts?
Yes, recipes need to be changed as well. 


The most important [IMHO] difference is leavening (yeast/baking powder/soda etc.) 
The next issue is ratios, once you get beyond 'doubling' a home recipe your ratios will get out of sync.
When you multiply dry ingredients (other than yeast) do so By Weight rather than dry measure. (note for sugars in a yeast leavened recipe: sugar is often 'treated as' a 'wet ingredient', still multiply by weight, this will provide the correct amount of food for the yeast)



  Rule of thumb for yeast baking is to multiply everything but DO NOT
  multiply the yeast for doing 2X or 4X. When you are increasing the
  recipe by 8X you double the original amount of yeast. Your rising time
  may increase but that also happens with temperature variations.
  
  Rule of thumb for chemical leavening is to multiply carefully ALL
  ingredients. If using baking soda and acid, sift the baking soda with
  flour and mix the acid (vinegar, lemon juice, sour milk) with other
  liquid ingredients. That way you don't lose rising power when mixing
  more dough. 
  But for chemical leavening, you have to bake the mix without it
  sitting around. So you might weigh and set up 4X, 4X, 4X if you need
  12X yield.[from King Arthur Flour]
  





  Home sized recipes can usually only be doubled safely. Beyond that,
  due to rounding, the ratios within the recipe will get out of sync. We
  have a number of pro resources here, take a look:
  http://www.kingarthurflour.com/professional/flours.html(Ibid) 




These are, obviously, only 'general guidelines, your mileage may vary with any given recipe.