Can also confirm this - the research team I used to work on was just three people. We worked directly with some 30 or so funds, successfully, including Citadel and Two Sigma.
Did you find the work to be intellectually satisfying and creative, or was it somewhat rote in the sense of having to spend lots of energy on data hygiene?
I found it to be very intellectually satisfying and creative! But there were parts to the job which were also very boring, including cleaning data. Cleaning data took up probably about as much time as all the fun analysis and exploration.
What software is used in the cleaning and analysis?
By hand one Excel cell at a time :) It's why they get paid well.
I never used Excel, except to present reports. Data warehousing and analysis all took place with SQL and an RDBMS.
This is fascinating. Have you been working for a bigger company back then or was it an independent gig?