Furniture

Yes - furniture must be included in LEED-CI: "Regardless of who specifies or provides them, all furniture and furnishings in the project should be included in the calculations for LEED for Commercial Interiors." (see page 208 in the ID+C v2009 Reference Guide for the full quote/section).

If you don't include the furnishings, you will also run into conflicts with general rating system eligibility. As outlined in LEED Interpretation 10102: "For LEED for Commercial Interiors and LEED for Retail: Commercial Interiors projects, spaces are considered incomplete if they do not include the furnishings, fixtures, and equipment (FF&E) intended for regular operations of the space."

For any project registering after that LEED Interpretation posting (11/1/11), at least 60% of the floor area must be considered complete to even be eligible to submit under LEED-CI (i.e. with all necessary FF+E). If you registered before that LEED Interpretation posting (11/1/11), you were technically held to the LEED Rating System Selection Guidance which required at least 40% of your area to meet the requirements of the system to be eligible.

So submitting without any furnishings included is not allowed in LEED-CI; you'd need to have at least 60% or 40% of the space fully fit-out for use in order to comply with the basic rating system requirements and that LI (percentage depends upon your registration date).

In NC, the furniture must be included across all MR credits if you want to include it in any of the MR credits . You can choose to include furniture or not in that case.

In CI, the furniture must be included as a rule across all MR credits. There is no choice.

Correct - in LEED-CI, furniture must be included in the MR credits. If the project is coming through LEED-CI, you will need to make sure that it is include in all of your attempted MR credits.

For furniture assemblies with wood - you would need to follow the assembly calculation method to calculate the amount of new wood in the overall assembly (by weight) to then determine how much of that product is comprised of new wood and is applicable to this credit (MRc7).

As an extra note - if you intend to submit with only a portion of the space fully fit-out (i.e. only a portion with all FF+E as required for operation), please make sure to very closely read LI 10102 as there is quite a bit of extra documentation and work required to confirm compliance for the remaining incomplete areas (i.e. the areas that don't yet have all FF+E as required for operation). It's a complex one to keep your eye on closely if you are thinking of going that route.