Good morning. What is your city and state so I can look at snow loading?
For scenario 1 you can plan for a W14x34 steel beam ASTM A992 Gr. 50 (you will need to have the joist connection detailed to brace the beam against lateral torsional buckling) or a 7" x 20" 2.0E LVL
The 24" LVL is fine, but the I beams are not large enough.
Hello. Do you have any other questions on this topic? If you could rate my answer, I would appreciate it.