What is the fee for mixing the coins or it is free of cost like other mixers ?
We need to mix around 8 dollars (0.001 BTC) in order to participate which is a little high.
Using SmartMixer for mixing your coins is not totally free, not the same with other mixers which you can decide how much fee you will pay.
But as I found about the fee of SmartMixer is quite low and affordable.
You can find the information about the Fees of SmartMixer here:
https://www.smartmixer.io/en/fees
Is this competition is more likely random pickings of the winners?
Like even we have 1 entry, we still have the chance to win since if they will draw the contest randomly while having more entries (not more than 5 entries) is more chances of winning.
Quick tip for everyone who is planning to join and choose Bitcoin to mix, checking
Bitcoin fee before sending your coin to be mixed is good to save mo Bitcoins is miner's fee, like 1 satoshi per byte is good for some small amount of bitcoins to be sent.