Industrial Outdoor Cantilever Shelving Unit

This will depend largely on what you're accessing the product with. The main issue will be that you don't want to strand product at the back of the racks. A reach truck can reach into deep racking but a standard forklift will not be able to access items that are further back than a standard pallet depth. You will also need to consider what you are storing. Anything that is inclined to roll, such as pipes or timber may slip off and pose a safety risk, unless they are able to be placed well onto the arms of the forks. A product such as flat wood is more likely to be reached and carried securely from deeper racking.

No, cantilever racking can be built on a standard concrete floor. They can even go outside on tarmac, as long as the weight is spread to avoid particular legs from sinking. Your racking experts may suggest a footplate, with a big I-Section beam on the bottom, spreading the weight between the different piles. In this way, cantilever racking can have minimal problem with puncture weight.

This will depend on the structure of the wall. In almost all cases it would not be possible to tie racking into the structure of the building, as you won't have information on the type of strains the building is already under.

Heavy racking can affect the dynamic loads placed on the walls, such as wind tolerance. You also don't want to interfere with the weights going down the building's columns as this risks structural instability. 

However, there may be an exception if you plan to build racking within the walls or columns when planning a new building. In this case, the engineers can account for the additional weights and plan the structure accordingly.