Wa alaikum assalam,
1. Lateral force resisting system (LFRS) is selected primarily based on the seismic zoning (or seismic category) of the area in which a building or structure is to constructed. LFRS selection partially depends upon the preferred material of construction (e.g., Reinforced Concrete, Structural steel, etc) as well.
2. if you don't have load bearing walls in your structure to transfer superstructure ( floor and roof ) loads to the foundation, it is NOT a 'load bearing wall system'.
3. A 'moment resisting system' is the one in which beams and columns are used to transfer the superstructure loads to the foundation. The walls provided in this type of structure are commonly termed as 'infill walls' or non-load bearing walls.
HTH
Regards.