2. QGIS is actually “better” at interpreting OSM than Arc, simply because people who work on free software like free data and there are many more plugins and tutorials that are based around OSM for QGIS. So it’s not “better” in the sense you might be implying, more like it’s just a much more typical dataset for the QGIS community than Arc and you reap the side benefits of that.
As other poster noted as well, the commercial options for QGIS sat the moment are not very good. I think Desktop GIS is an area that is ripe for Gitlab-esque disruption.
FME is an ETL tool, using it just for the Data Inspector part would be a waste. In this scenario, QGIS would be also more comfortable and user friendly. On the other hand, QGIS cannot do what is FME's primary use - transform data.