Looking for information on tracks of the D&RGW (rails, ballast,..)

Hi,

I'm just compiling information for a small article I'm going to write for the FREMO magazine about track on the D&RGW narrow gauge
(FREMO is Europe's biggest(?) model railroad club, with a quarterly club magazine)

Although the main focus of the article is a #8 1/2 turnout, where I researched a lot of information already, I also want to provide information of basic track there.

A few questions are still open, maybe someone knows more details.
Specifically I'm interested in the 1940-1950 era, I guess from that on
there was not changed much until end of operation anyway.
I'm mostly interested in the D&RGW, but if anyone has information for the Rio Grande Southern, I'm interested in those as well.

a.) rail sizes; Once someone gave me a fact sheet for the Cumbres & Toltec, stating, in 1922 there was 70lbs rail laid and from MP 316.87 to 342.53 in 1936 there was even 85lbs rail used.
Questions:
Is it safe to assume, that all track of the D&RGW narrow gauge in the 1940-1950 era was 70lbs or 85lbs?
Or were there some sidings with smaller profile at that time? Does anyone know the height of the 70lbs and 85lbs profile used? (I've measured it, but measurement are just approximate)
Which profile was used in dual gauge track?
What rail did the Rio Grande Southern use during this time?

b.) rail length + tie spacing
What was the typical length of rail? 30'? What was the common tie spacing?

c.) ties
Were ties treated or raw wood? Most of the ties I've seen don't look treated, but that might just be not visible after all these years.

d.) ballast
What was the ballast used? I've seen some sidings, where it looks like it was simply dirt and some tracks, where the ballast was very fine-grained (I don't know the exakt word for the material)

Thank you in advance!

Christian