What will happen to my transfered ETH if it will be not enough for 50$? And what will happen if I transfer more than 50$, but the ETH rate will suddenly drop and the transfered amount will become less than 50$? Imho, it was a bad idea to indicate the requiered sum in USD.

In other ICOs I just buy tokens and they are being tied up to my ETH wallet automatically. Why do I need to manually add tokens to my wallet using metamask here?