FEM types
According to the method of obtaining the basic, i.e. resolving, equations, there are four main types of the finite element method: direct, variational, weighted residuals and energy balance.
What is the default view? Can I choose other methods?
FEniCS is based on weak formulations, using the unified form language (UFL). How you choose to derive your weak formulation from a strong formulation, is up to you.
Second to @dokkenās suggetion, Iād recommend reading some of the introductory literature. Doing so will elucidate the philosophy and simple code examples of FEniCS almost immediately. For example the Hughes book.