Production Buildings radius and placement

I have two questions about the placement of Production Buildings in Anno 1404:

1. What is the Radius of a production building all about? I.e. if i have an iron smelter it shows me a radius for the building. What does this radius mean?
2. Do ressources need to go to the warehouse, even if the production facility which needs them is on the way? I.e. I have the buildings in this order: Iron Mine - Iron Smelter - Warehouse If the market cart gets iron ore from the mine, does it drop it at the iron smelter or will it bring the ore firstly to the warehouse and then another (or maybe the same cart) will carry it to the iron smelter?

Production buildings that requires moveable/storable resources have a radius (A, destination). If another building producing the required resource (B, source) is within that radius, journeymen will bring resources from source to destination. When placing or selecting a destination building, any valid source building turns green.

Market Buildings also count as valid sources for any resource they contain.

In this screenshot, the Weapon Smithy is currently selected and shows, in green, buildings within its radius that can provide it with its required resource: Iron. It could come from the Iron Smelter above, or from the Market Building to the left (assuming it has some in storage).

When you set things up this way, whether there's a road connecting the buildings or not, you will see a journeyman carrying materials by walking straight from one building to the other:

Also, you can have multiple destination buildings provisioned by the same first tier buildings: 3 hemp buildings -> 2 weavers. From observation, the weavers will go pick hemp from wherever it's available within range.

I've started experimenting with this and I get the feeling it's a good way to improve production chains:

• Journeymen appear even if there's no road
  • This can free precious tiles for fields, or simply placing related buildings right next to each other
• They walk straight to the other building
• They do not count as carts, so there's no limit to how many you can have

Possibles issues:

• They're slower than carts, especially carts on paved roads
  • Putting buildings as close to each other as possible helps with this
  • I see no way to improve their speed in the rare cases it might be needed
  • It doesn't matter that much since production speed is often the slow part
• They have lower carrying capacity (3 units instead of 5)
  • Again, might not matter much since they'll usually be faster than production

Another point of interest: since roads are not needed, you can leave first tier buildings unconnected:

• Carts won't pick anything up from these buildings and focus on other important resources (such as end products).
• These buildings end up "dedicated" to a small number of destinations
  • This ensures there will always be enough material for the destinations, as long as you have enough source buildings
  • It's easy to check how many source buildings you need for a given number of destination buildings. Just check their local inventory, see if they're often at 0 (you need more) or if they stabilize at 1 or more (good) or if they keep filling up (you can have more destinations)

Based on this, I've started building "local chains" with dedicated roadless buildings, and adding a single road-connected extra source building to build up island-wide storage, just in case and/or for selling/quests.

For example: 2 Hemp -> 1 Weaver + 1 Hemp for storage

Finally, to answer your second question: carts seem to only travel from the warehouse to a building to pick up stuff and bring it back to the warehouse. I've never seen them drop resources where it was needed on the way. I once tried having a destination building with no source building nor Market Building within range. Well... it remained resourceless.