Welcome to the forum Battenhatch! :-)
Melee attacks
Melee (including unarmed combat) typically only have an Attack Rating for the Close range category.
It is assumed that you can typically hit anyone within this range with a melee weapon (without spending a minor Move action).
Note that in some cases the Close range category is extended from 3 meters to 5 meters. For example if you have the Long Reach Positive Quality.
Multiple attacks
When you have one dice pool then you try to divide the number of dice in the pool as evenly as possible over your targets.
For example: If you are attacking with a Sword in your right hand and a Knife in your left hand and you wish to attack the same target twice (once with each weapon) then you would take your Agility + Close Combat dice pool and divide it between the two attacks. If it is an uneven number (say 13 dice) then you get one dice more on one of the attacks (in this case your sword attack by your main hand would probably get 7 dice.... in which case the knife attack in your offhand would get the remaining 6 dice).
When you have two different forms of attacks (two different dice pools) then you typically split the pools individually instead (and round down).
For example: If you are attacking with a pistol in one hand and a katana in your other hand then you would take your Agility + Firearms pool and split it in two (round down) for your pistol attack and your Agility + Close Combat pool and split it in two (round down) for your Katana attack. If you have an Agility of 6, a Firearms skill of 6 and a Close Combat skill of 3 then your Pistol attack would end up with 12/2=6 dice while your katana attack would end up with 9/2=4 dice.
How did it finally end up with unarmed base damage?
Unarmed Combat base DV = 2 (Stun).
Unarmed Combat Attack Rating = Strength + Reaction.