Structured financial data should be prepared beforehand. Unstructured data can be found in trade magasines, from customers, tenders, promotions, homepages etc.
Assumptions about the competitors strategy requires deep industry knowledge. If you do not have this knowledge you should prepare the information in a larger group.
A workshop should be focused on:
1) What are the best in the business doing, and what have they done to achieve their position?
How have they done it?. What separates the «best» from the others? This is a good guess for the Key Success Factors (KSF).
2) What are the criterias for competetion? Price, differentiation, access? What can we do differently to:
Avoid direct competetion? Fill an available position in the market? Are there any niches that noone is focusing on? Are there any customers with unmet needs?
3) Are mostly your competitors focused on a few key success factors (functonality? Innovation? brand building?)
This could mean the market is ready for disruptive innovations or blue ocean strategies.
A competitor profil that describes the competitors resources, competitive advantages, processes, strengths and weaknesses is important input to the creative strategy work.
See Example here.