References for Yang-Mills Theory
If your goal is to get some understanding of the Clay Problem, you can't really go wrong with first reading the official problem statement and then reading the papers referred to in the document.
On the other hand, if your goal is not the quantum problem but more the classical problem, for the geometers and algebraists a good starting point is of course Donaldson's Geometry of four-manifolds which contains a lot of classical results in the direction (and you can use the reference list to find the original papers should you wish). Donaldson's more recent survey can also be a point of departure.
Since you mentioned that there are participants interested in curvature and Ricci flows, you can also consider discussing the results related to the Yang-Mills heat flow. The standard references are
Johan Råde, MR 1179335 On the Yang-Mills heat equation in two and three dimensions, J. Reine Angew. Math. 431 (1992), 123--163.
Andreas E. Schlatter, Michael Struwe, and A. Shadi Tahvildar-Zadeh, MR 1600272 Global existence of the equivariant Yang-Mills heat flow in four space dimensions, Amer. J. Math. 120 (1998), no. 1, 117--128.
If you also want to discuss the hyperbolic initial value problem, then a good (classical) place to start would be
- Eardley and Moncrief MathSciNet link
- Choquet-Bruhat and Christodoulou MathSciNet link
There has been a lot of development/improvement/extensions since then (see the References link in mathscinet) but they tend to get very technical very fast (into the details of PDE theory for wave equations) and may be less interesting for your stated audience.
You could start with Terence Tao's Local well-posedness of the Yang-Mills equation in the Temporal Gauge below the energy norm, available online via the arXiv.
A second paper by Tao and Gang Tian on the subject is A singularity removal theorem for Yang-Mills fields in higher dimensions, also available via the arXiv.