When selecting fields to convert is there a way to select all within QGIS? I'm currently alternating space bar and a down arrow and this does not seem to be the most efficient method.
You don't mention which version of QGIS you're using. I'm using 2.16.0 and this dialog has a 'select all' option:-
Not used this function for a while now so I'm not sure when this was implemented,
although I'm guessing it's probably in QGIS 2.x. but it seems to have been in 2.10 according to this commit
I changed to using QuickOSM plugin (for small areas) or PostGRES/osm2pgsql (for country-sized or larger) based on protobuf extracts (which are much more compact than .osm xml). These are options if you don't have a specific requirement or preference for osm xml/spatialite.