Gems

xs. buy a set of cards for them

The only working option is to transfer all the gems to the account of a reliable friend, and then transfer them back to your account. This is the only way gems can be combined into one cell, and then either combine them into a "Bag of Gems" (1 bag = 1000 gems) and put up on the trading floor (the cost varies, but, as a rule, is about $ 0.5), or create of the available gems, sets of cards.

yes, no difference, no, you think they are scattered, there is only one amount, exchange them better for experience cards yes you will upgrade the badge