QUESTIONS TO ANYONE WHO KNOWS (no guessing please)

1.  If I mined 10 million coins in first few days and intend to keep them for the POS minting, but I have also mined more since then, how does the wallet know which coins I transfer out to sell?  Does it take first in /first out or how does it really know? My guess is that there is no possible way and this is a major hiccup in the code.

2.  If it pays POS before mining is complete (down to 1 coin per block) how does it know if coins have already been paid the POS or not?   If I buy 1 million from someone who got their POS payment, those have been paid the first payment.  But if I am still mining 1 million also, how does the system know which coins are new and which are old?  Another serious flaw I am thinking.  Uless the POS starts after the reward drops to 1 coin.  

I realize everyone here is a genious and has their belief, but I want an accurate answer as the answer is very importnat and depending on it, there is a potential HUGE arbitrage situation in the making.