Obviously this is quite a broad question, so I may as well note that I am principally interested in Western Europe and North America. I'm familiar enough in general terms with a few of the major conflicts of this period and region in operational terms (e.g. the Crimean War, Italian and German Wars of Unification, American Civil War), but I've never been that up to speed on the particular tactics involved. A few sub-questions I guess, just to make clear a few of the things I'm angling at:

Thinking purely technologically here, quickly if at all did the introduction of rifled muskets and artillery affect tactics, and ditto for breechloading?

How far was general 'quality' of troops (in terms of training, mainly) a significant factor? So for instance I'm aware the American Civil War gets cited as a case of rifled muskets not significantly affecting battlefield casualties compared to say the Napoleonic Wars, but would the militia armies of the Civil War be particularly comparable to some of the better forces of the Napoleonic period? Would a more viable comparison be to the Crimean War given that the armies involved were the direct successors of the Napoleonic forces?