I finally got my first coins, 1.5 BLK with 10200 BLK on stake. Price must go at least to 1$ or this operation is not economical approved for investments under 10k$. I'm not en expert but I see if you have more coins you will get better share and you will get it faster. Why this time until reward is not same for all included wallets? I hope exchanges do not have ability to stake.
Sorry I have to say that, but demanding that in a PoS system is like asking for equal chances to mine BTC regardless of the hash power.
Exchanges can of course stake as everyone with an online and unlocked wallet - they would be fools to do so though as people could see that they don't use cold wallets.