[zenith]

To answer a few questions...

You can purchase the same implant multiple times. Each time will be +1 to the stat, and will cost the same amount of humanity. The price will increase each rating point similar to the cost of upgrading gangs.

You can purchase any combination of cyberware. Since they are all slightly different, each one will benefit from the other as every cyberware option uses some form of computers and synthetic human tissue. Remember though, your humanity level is extremely slow at increasing, so you will have to balance your purchases with your humanity rating.

The rating is a bonus to your natural stat rating. So a +1 accuracy is a plus 1 to your accuracy rating. Buy it again and you get another +1. Your max modifier to any stat is 50% of your natural rating rounded down.

Tie-breakers in combat will always favor natural ratings. Weapon requirements are based on natural ratings as well, so no one can just buy their way to the top.