Gaute: Spatial tensor product of C*-algebras (Murphy, Sections 6.3-6.4, particularly Theorems 6.4.18, 6.4.19)
Tobias: Morita equivalence (Lance, Hilbert C*-modules, Chapter 7)
Erik: Group C*-algebras and amenability (Davidson, Sections VII.1-VII.2) (may restrict to discrete groups)
Sveinung: The reduced C*-algebra of a free group is projectionless (Davidson, Section VII.8)