This is a study of the effect of electron-phonon interactions on the spectrum and transport properties of Dirac electrons in metallic single-wall carbon nanotubes. It is shown that the pseudomagnetic part of the interaction potential of electrons with transverse acoustic phonons induces a gap in the electron spectrum. Two mechanisms for formation of a gap are considered: Peierls phase transitions and a correlation mechanism owing to virtual exchange of electrons with transverse phonons. The scattering probability of massive Dirac fermions on a scalar (electrostatic) potential of finite size is calculated and the renormalization of the bare scattering amplitude induced by electron-electron correlations is evaluated.