To start the building you need to have 15M iron, 10M silver, 2500 Ale, 2000 Timber, 2000 Stones and 100 Scrolls. It is not possible to use Gold for upgrade. Building time for level 1 is 1w/3d. Only the Chief or any of the Elders can start a construction process, but all clan members can send rss to the Stronghold Resource Storage.
For speeding up the building process or the smelting process you use a Stronghold Boost.
The Smelters' Yard converts Iron into Steel.
For level 1 the stats are
Maximum of Steel received: 2000
Stronghold Influence: +62M
(someone else can make a proper table later)