Stain will bleed under tape, and maybe even bleed under the finish applied on the heel.
I suppose you have a reason for wanting to stain it, but you will probably have to sand the edges for a final fit which would remove stain applied before installation.
A color contrast usually looks good for a heel cap.
As to finish, it is difficult to say without knowing what the finish is on the neck heel.
I don't use lacquer, but know some finishes do not get along well with lacquer, so if it is lacquer i would use spray on lacquer.
Otherwise I would probably use either Minwax wipe on poly, or Birchwood Casey Tru-Oil (I do not know if either of these will work with lacquer).