The "stake" is the coins that recently participated in a PoS block generation. After 50 blocks they are returned to the normal state and in 5 days will get old enough to participate in the PoS generation again. You will never see all your coins in a stake unless you merge all of them in a single input by merging them together by sending to yourself the whole amount. There is no reason in doing this IMO, as any coin has fixed maximum number of 'cycles' per year. You can't use your coins while they are in stake, but the coin age for these coins is reset at the moment of PoS block generation, so by merging them manually you reset the coin age to zero again, thus you extend the period of being not eligible for the transferred this way coins.
So min coinage is 5 days??
Yes, the input must be at least
Edit: Sorry, fixed mistake.
