That is an excellent article and I really appreciate you sharing it. I don't pretend to know what inflation rate would be ideal (nor do I think anyone could know for all time what it would be), but instead, an arbitrary, but informed, decsion would need to be made about the inflation amount, just like with the arbitrary limit of 21 million Bitcoins.
Developing a wide index of prices (precious and semi-precious metals, international price indices, etc) would be the difficult part. Reading in those values each day to determine if and how much demand exists for reward coins is less difficult.
I don't think this would be needed, as the inflation amount would be a hard limit included as part of the protocol.
New altcoins are less known, are accepted by fewer vendors, and will be seen on fewer exchanges. Early adopters need a real incentive to download the wallet and CPU-mine, but that increase can decline as such an altcoin becomes more widely used.
I believe the model laid out by Satoshi is correct, higher rewards at the beginning and diminishing over time. I am just not sure that the reward should diminish to zero.