With all the photos coming in from your field teams (15,000+ from a ten day study), you need tools and a process to effectively manage your data. Adobe Lightroom is far from perfect but it is easy enough for a just-hired field assistant to use to import, tag, rename and export photos ready to be used in the work flow.
A spare laptop dedicated for data processing makes the process easier to manage, and is good for overnight batch processing (renaming, resizing, tagging, …) – and we often assign one member of the team to take the role of data manager. Data doesn’t really exist unless it’s copied in multiple locations, though whether you use external drives and the security on those drives depends on the sensitivity of the data you are collecting.