1-- Either is fine.
2-- Firstly and lastly replace first and last in enumerating e.g. steps (First[ly], one opens the battery case; second[ly], one inserts two AAA batteries...), but do not normally occur in other formations. I myself consider these -ly forms awkward, useless and rather pompous hypercorrections, and I have my students avoid them in their writing.
Student or Learner