So as everyone keeps coming up with these new coins and new algorithms, how do they decide how many total coins to offer? I know LTC is exactly 4X as many BTC. Can anyone shed any light on this, or is it completely random and up to each individual coin maker? What are the possible positive and negative impacts on a somewhat random, finiate amount of coins?
You already had many good answers to you question. I also think it is important to mention that the "coin makers" (called devs) can chose to add a "premine" to the genesis block (the first block). The word premine is a bit misleading, since nothing is being mined, they have simply started with giving themselves x millions coins as a rewards for making a new revolutionary coins that everyone should invest in.
I don't know if "revolutionary" is really the proper term to use. Most alt coins provide no value that bitcoin cannot provide and their network is much less secure then the bitcoin network.