Design of Physical Steel Beams with Intermediate Nodes

What is the right way to model and design steel beams with timber floor joists in STAAD Pro? I have a series of 65 ft. long steel beams supporting timber floor joists at approx. 16 in. spacing (Please see picture below). The steel beams have several intermediate nodes between supports to accommodate the floor joists. The problems is the analyses output is generated for thousands of 16 in. long steel beams instead of the expected 65 ft. beams, making it difficult to review. I also realized the bending resistance is based on yield strength instead of buckling (which is most likely to control for the selected beam). The challenges I encountered are summarized in the following questions:

1. How do I perform design on physical beams rather than based on node-to-node length (Note: the steel beams are already grouped using the physical member command)?
2. How do I perform buckling analysis using actual physical lengths of the beams (I have given the LX, LY, LZ, UNB, and UNT parameters before analysis but that doesn't seem to change anything)?
3. How do I make STAAD to not consider the floor joists as lateral bracing since the timber joists are just resting on the steel beams?