I do remember clearly the times with 400k XMR on sale.

Plus ya got the coolest avatar on the board LOL

0.3 XMR per minute. Now that block times are 2 minutes, the subsidy is 0.6 XMR.

1) It has an adaptive blocksize limit with a minimum emission of 0.6 XMR. ...

... insignificant  value compared to just being their, bags full, when the moves come.

Ignoring for the moment that mining efficiency is what will separate those who thrive, from those who survive, and those who fade away as mining cryptocoins profitably continues to get more difficult, and that I want to be in the group that thrives, it is simply not in my nature to provide services without compensation.  You're in luck though because many people are considerably more altruistic than me, and almost everything I have learned about this subject probably started right here on [Suspicious link removed]o just start searching and there is nothing you won't find.  Almost everything there is to know on this topic has already been written...

Simply stated, intensity is used to allocate memory for the scrypt buffer as a power of 2.  For intensity 13, 2 ^ 13 = 8192, intensity 20, 2 ^ 20 = 1048576.  So for each step up in intensity, the greater the jump to the next memory allocation setting on the exponential scale.  Xintensity in sgminer can be tuned on a much finer scale as it is not based upon powers of 2.  There are so many other variables contributing to optimal configuration that I will not mention them here, but there is plenty of information available out there if you really want to learn how it all works.  There are many nuances that vary by type of hardware, and simply increasing speed does not necessarily reap performance improvements.  And then you really need to evaluate if any performance improvements achieved are actually cost efficient.