1) Travel within an exit (i.e., enclosed exit stairway or ramp, exit passageway, exterior exit stair) is also not included in the travel distance. Travel distance is measured from the most remote location in a space to the entrance of an exit. Once and exit is reached, travel distance is no longer measured. For example, you could technically travel thousands of feet within an exit passageway before reaching the exit discharge.
2) If FF&E create aisles that only provide a single path, then yes, that would be considered a common path of egress travel.
3) I skipped #8 apparently. My #8 response was meant for your #9 question. So, to answer your #8 question, the occupant load of the doors at the level of exit discharge shall be based on the greater of the occupant loads using the exit. The occupant loads of floors above or below are not compounded (See Section 1004.1.1.3, 2015 IBC). However, converging loads are per Section 1005.6 (2015 IBC). Thus, the occupant load of the ground floor is not added to the converging occupant loads of the basement and 2nd story. The basement story is permitted to have a single exit if the occupant load is less than 50 per IBC Table 1006.3.2(2); thus, all 20 occupants can egress up a single stairway. The 2nd story is required to have two exits, so the 100 occupants must be split between both exits; thus, one exit will have 50 and the other will have 50. The ground floor, with 80 occupants, is also required to have two exits with an even split, as well (40 and 40). Only 50% of the exits is permitted to egress through a lobby on the level of exit discharge (Section 1028.1, Exception 1). So if one of the stairs egresses through the lobby, the size of one of the exit doors on the ground floor will be based on the greater of the two occupant loads (40 occupants from the ground floor or 70 occupants from the converged occupant loads [50 + 20 = 70] of the basement and 2nd story), which will be the converging occupant loads. The second exit from the 2nd story must egress directly to the exterior, so those 50 occupants are not added to the occupant load on the ground floor.