the sidemirrors you are looking for are usually available in markets where old datsun sunny 1200 parts are sold.
the seats you bought will not fit unless you bash in the floor or trans tunnel, the best and eventual low cost option would be to rework the original seat chassis with new finishwork.
Finishwork is not "aam seat ki dukaan" - anyone can stretch some vinyl, but it takes a craftsman to make something beautiful.