We've been doing research on new methods/tools for placing items at a distance. One is more accurate, but doesn't give as much distance. It's called stick. The other can give greater distance, but accuracy can be a problem. It's called throwing.
Not really, assuming the water isn't that deep you could wade out and harvest that way. Plenty of food plants are grown and harvested in water like this.
From the looks of it there is a considerable outer layer of lighter plants that are likely required to have a good plant-mass to flotation device ratio, but this layer makes it hard to access the inner plants that could be used as food crops.
If a similar approach was used for crops, they could be pulled to shore or accessed with boats. In either case, they could be formed as long narrow strips instead of circles or squares to easily access the crop portion.
Yes, but to "harvest" such plants they just need to pull them out of the water and compost them somewhere. Not quite the same as harvesting some actual food product.