I am working on a book-length manusript, Around the Chevalley-WarningChevalley–Warning Theorem. A complete answer to your question is estimated at about 150 pages!
In terms of what exists at the moment, here are two papers. Both of them make connections between the classical results of Chevalley and Warning and modern polynomial methods. The first concerns a generalization of the (unjustly almost forgotten) Warning's Second Theorem to restricted variables. The second explains the connection between Chevalley's Theorem and Alon's Combinatorial Nullstellensatz. I take the perspective that the Combinatorial Nullstellensatz is in fact a very direct generalization of Chevalley's proof of Chevalley's Theorem. (I don't mean "very direct" as a slight against Alon: I am certainly a fan. Rather it is meant to indicate a useful --— at least for a number theorist --— way of thinking about these results.)
I'm afraid the above seems overly self-promotional. Let me also give what I think are the most important papers in this area, with an emphasis on relatively elementary work. [So I will not list e.g. work of Esnault, though I agree with Daniel Loughran's suggestion that it is, at least in some sense, the most important result of Chevalley-WarningChevalley–Warning type.]
J. Ax, \emph{Zeroes of polynomials over finite fields}Zeroes of polynomials over finite fields. Amer. J. Math. 86 (1964), 255-–261255–261.
C. Chevalley, \emph{D'emonstration d’une hypoth`ese de M. ArtinDémonstration d’une hypothèse de M. Artin.} Abh. Math. Sem. Univ. Hamburg 11 (1935), 73–-7573–75.
D.R. Heath-Brown, \emph{On Chevalley-Warning theorems}On Chevalley–Warning theorems. (Russian. Russian summary) Uspekhi Mat. Nauk 66 (2011), no. 2(398), 223--232;223–232; translation in Russian Math. Surveys 66 (2011), no. 2, 427-–436427–436.
D.J. Katz, \emph{Point count divisibility for algebraic sets over $\mathbb{Z}/p^{\ell}\mathbb{Z}$ and other finite principal rings}Point count divisibility for algebraic sets over $\mathbb{Z} / p^{ \ell } \mathbb{Z}$ and other finite principal rings. Proc. Amer. Math. Soc. 137 (2009), 4065-–40754065–4075.
N.M. Katz, \emph{On a theorem of Ax}On a theorem of Ax. Amer. J. Math. 93 (1971), 485-–499485–499.
M. Marshall and G. Ramage, \emph{Zeros of polynomials over finite principal ideal rings}Zeros of polynomials over finite principal ideal rings. Proc. Amer. Math. Soc. 49 (1975), 35-–3835–38.
O. Moreno and C.J. Moreno, \emph{Improvements of the Chevalley-Warning and the Ax-Katz theorems}Improvements of the Chevalley–Warning and the Ax–Katz theorems. Amer. J. Math. 117 (1995), 241--244241–244.
S.H. Schanuel, \emph{An extension of Chevalley's theorem to congruences modulo prime powers}An extension of Chevalley's theorem to congruences modulo prime powers. J. Number Theory 6 (1974), 284-–290284–290.
G. Terjanian, \emph{Sur les corps finis}Sur les corps finis. C. R. Acad. Sci. Paris S'er. A-B 262 (1966), A167-–A169A167–A169.
D.Q. Wan, \emph{An elementary proof of a theorem of Katz}An elementary proof of a theorem of Katz. Amer Amer. J. Math. 111 (1989), 1-–81–8.
E. Warning, \emph{Bemerkung zur vorstehenden Arbeit von Herrn Chevalley}Bemerkung zur vorstehenden Arbeit von Herrn Chevalley. AbhAbh. Math. Sem. Hamburg 11 (1935), 76–-8376–83.
Less than a year ago I thought there were about ten papers which generalize and refine the Chevalley-Warning Theorem. I now think I was off by a full order of magnitude, and indeed my current bibliography contains about 100 references. (I will admit that at this point, the radius of the circle referred to in Around the Chevalley-WarningChevalley–Warning Theorem is rather large. It includes for instance material on Davenport constants and on polynomial interpolation.)