Taking the irrationality problem for very general cubic n-folds as motivating example, we explore the possibility to use entropy-type invariants (dynamical degrees) and growth behaviour of Cremona multidegrees of birational self-maps for distinguishing birational automorphism groups of nearly rational varieties. We discuss some recent results (semi-continuity properties of dynamical degrees, computations of dynamical degrees for some compositions of reflections on cubic fourfolds, relation to algebraic subgroups of the birational automorphism groups) obtained jointly with H.-Chr. v. Bothmer and P. Sosna.

Manin's conjecture is a conjectural asymptotic formula for the counting function of rational points of bounded height on Fano varieties, however the conjecture admits many counterexamples due to covering families of subvarieties violating compatibility of Manin's conjecture. In this talk, I will explain how one can use the minimal model program and the boundedness of log Fano varieties to prove a sort of finiteness of such families. This is joint work with Brian Lehmann and Yuri Tschinkel.