The photoionization and structure of the superheavy elements No (Nobelium, Z=102), Cn (Copernicium, Z=112) and Og (Oganesson, Z=118) have been studied using Dirac-Fock (DF) and relativistic-random-phase approximation (RRPA) methods, respectively. The structure calculations reveal an unusual order of the inner-shell binding energies brought about by the relativistic effects, particularly the spin-orbit interaction, while the valence-shell structure of Cn is also anomalous owing to relativity. Photoionization cross sections and dipole photoelectron angular distributions were calculated from threshold to 35 a.u., 50 a.u. and 60 a.u. for the three atoms, respectively, and all subshells contributing to the total cross section in these energy regions have been considered. The resulting cross sections are dominated by interchannel coupling; the dominant subshell cross sections exerting very considerable influence upon the smaller cross sections. Using the feature of RRPA which allows us to omit particular couplings among the photoionization channels, we are able to pinpoint the crucial coupling(s) in various situations. Finally, using the example of Cn, we have investigated the structure and photoionization of Cn confined in a C₆₀ molecule, Cn@C₆₀, to study how a superheavy atom behaves under confinement conditions.