Resolve argument on load bearing walls
You really want to hire an expert. A house is probably the most expensive thing you will ever own; don't risk it if there is any doubt.

Usually, walls which run perpendicular to floor joists are assumed to be  load bearing until proven otherwise. That doesn't mean walls along floor joists are  not load bearing, but it's much less likely.

In older houses, walls may be carrying structural load even when they were not originally intended to, due to subsidence or past modifications.

Note that even load bearing walls can be opened up, by putting in a beam to take up the load and columns to transfer that load to adequate supporting points. Did that in my place, opening a 10-foot-wide passageway.  But that really calls for an engineer to determine what will have to replace the wall, and involves building a temporary wall alongside it to take the weight during this process.... In my case the final result needed a double Paralam beam across the opening (equivalent to a hardwood 12x4 beam?), similar manufactured-lumber columns from that down to foundation and joist, and we had to sister that joist with a steel C-beam in the basement to help transfer load to the foundation and main beam. Definitely not something to attempt without expert on-site advice.