hi,

I guess it depends on mainly two parameters:

• The long term nominal interest rate.
• How developed the ecosystem of "mining wallets" (service providers that act as traditional wallets + insure a fixed interest rate to coin holders) will be.

During the infancy of the coin, since distribution is done through PoS reward (instead of PoW for Peercoin, Blackcoin etc...), the interest rate will be very high. Therefore, we expect the percentage of mining coins to be very high >80-90% (it's of course difficult to provide an exact number).
After the first years, as the coin becomes highly distributed - meaning most coin holders own <1/100,000th of the coin for instance - the role of the "mining wallet" will become increasingly important. The percentage of coins mining would probably drop to 50%, but this is of course only an educated guess.

Moreover, there are plenty of mechanism that could be easily implemented to increase the long-term mining participation without increasing the chosen maximum inflation.
For example, the mining interest rate could be a function of mining participation. Let's say a long-term inflation rate of 3% is deemed optimal and let's only 30% of the coin holders think it's worth mining for 3% a year, by implementing such a scheme, the miners' interest would be come 3%*10/3=10% . Therefore, the percentage of coins mining would increase and the inflation rate would be fixed at 3%.


PS: sorry I haven't answered your other questions yet. I'm a bit swamped but will definitely get to them when I get a moment