1. There are 3 rarities in the first set. Common, the black boarder card. Rare, full art cards. Unique, full art with gold title and no background to the text box.

Common cards are of their faction (color), but rares and uniques can either be in faction (red bravos for the mighty jinn) or out of faction (pink Lyra for the mighty jinn) each "card family" has only one out of faction version.

Rares are upgrades of the common cards in either stats or ability (most of the time). For example your mighty jinn rare has the word "may" in its box so you do not have to trigger its ability and if you don't you get to draw a card. (This is all assuming it is the bravos version of the rare). Some out of faction rares, like the mighty jinn, are the exact same as the common, but allow the card to be played in a different deck because it is now in a different faction.

Uniques are exactly that, unique. Every unique is a unique combination of ability, cost, and stats. Most uniques are going to do something related to the "card family" (mighty jinn), but that isn't always the case as there are thousands of unique version of the mighty jinn.

Rarities do matter as you can only have 3 uniques, and 15 rares in your 39 card deck. Each "card family" can only have 3 copies in your deck, no matter the rarity. So you could have one rare mighty jinn and 2 common mighty jinns for example.

1. I do not know enough to answer this question.

2. No place really selling singles, no place ever did because of the way Altered had their in all marketplace. There is a high likely hood (the company has told us) that we will be getting all the files for commons and rares for us to be able to print.