Funnels: White Star line funnels have been a subject of debate for YEARS. Sources will vary from a light peach/almond color to a dark brownish mustard color. Recently the WSL tender SS Nomadic was restored and supposedly the funnel color is a formula from Harland & Wolff records which shows it more on the yellow side. According to Walter Lord's description of the RMS Olympic funnels he states you could see a pronounced yellow in them.
It would appear you could mix it from flat yellow, white, and a buff color adjusting the ratio until the formula looks right.
More helpful color references. The decks on Titanic were yellow pine, there are several reccomendations in the second link down.
http://titanic-model.com/articles/paints/WEBPAGE_Photographic%20Records%20of%20White%20Star%20Buff/White_Star_Buff_Weighing_the_Evidence.htm
http://titanic-model.com/paint/
Railings: Toms Modelworks released a set of rails at the end of August 1:600 Scale Set No. 6010
The same manufacturer makes a deck bench set 6014, window frames 6013, and misc. details 6011
And here is a source for various scale anchor chain
http://www.modelshipbuilding.com/anchorchain.htm