It would be much easier to allow the Infopath form to submit to a Sharepoint document library and use the document library to expose and distribute the data.
If you truly must have content in an access database, that you store inside Sharepoint, which means you are basically storing it inside of sql serverm I would look into writing an event receiver for the document library you post the infopath forms into and let it extract the data and update the ms access database.
As far as the reference data, could you put that into lists in Sharepoint?
Providing this data in Ms Sql for Infopath would be the best approach, but using
Sharepoint lists will be easier to develop.