@Jason818: regarding specifics on the office interiors - they were real offices, decorated by each individual. MSFT employees get assigned blank offices (with windows if you have seniority on the team) that have standard equipment of corner desk, small worksurface, large worksurface, standard office chair, hanging bookshelf, hanging whiteboard and hanging corkboard. Once you take possession - you can equip / decorate / organize as you see fit with personal items. Some go so far as putting down area rugs, custom desks / chairs, treadmills, standing desks, couches, leather chairs - whatever!
Regarding the first Q you have (numbers on the wall) was to a race Mark was in a while back. Why extra shirts in Mark's office - he keeps spare ORANGE shirts just in case he needs to shoot a #pingshow.
As for ArtWork on the wall of Simons office - those are personally curated comic graphics he had mounted and hung on his wall. They arrived in his shipping container from the UK a couple of weeks back.
FYI: I have a comfy leather couch in my office and a "lounge" recliner chair next to my standing desk with dual monitors.