  We consider a finite-time quantum Otto heat engine that consists of two
isochoric (thermal-contact) process, where the system is alternatively coupled
to a hot squeezed and a cold thermal reservoir, and two unitary driven strokes,
where the system is isolated from these two baths and its von Neumann entropy
keeps constant. Both quantum inner friction and coherence are generated along
the driven stroke and coherence cannot be fully erased after the finite-time
hot isochore. Using full counting statistics, we present the probability
distribution functions of heat injection and total work per cycle, which are
dependent on the time duration along each process. With these, we derive the
analytical expressions for the thermodynamic quantities of the two-level heat
engine, such as total work, thermodynamic efficiency, entropy production, and
work fluctuations, in which effects of coherence, squeezing, inner friction and
finite-time heat exchange are included. We then numerically determine the
thermodynamic quantities and the fluctuations using the parameters employed in
the experimental implementation. Our results clarify the role of coherence and
squeezing in the performance and fluctuations in the quantum Otto engines.
