Re: C&S engine pool/freight mix

John:
Until 1936, #60 was the assigned switching and fire service engine at Leadville. Rarely used in freight service, but always under steam. It was taken to Denver for major overhaul in 1936 and was out of service for a long time.
Moguls were often rotated in and out of the freight pool, particularly #8.
Scheduled freight operations were two trains eastbound and two trains westbound per week.
The leased D&RGW engines were needed because of the wreck of #75 and #73 on Boreas in January 1936. #73 was not brought up the hill until the following summer. Abandonment came in April, 1937.
As you suggest, the C&S was required to keep 8 engines available for freight service 4 days a week, and two engines on Passenger every day. Additionally, as I said, #60 was always under steam at Leadville until early 1936 for fire and switching service, and there was always a hot engine at Como for emergency passenger service.
After #60 went into rotating service and overhaul in 1936, it was not replaced in Leadville with a dedicated engine.
Branchline service was performed on the Clear Creek off days from Main Line freight operations.