If you really think that all the period and apostrophe pairs are just kern pairs, with no difference in the outline, then I would delete these glyphs and implement the same effect with kern pairs instead.
I would otherwise put them in dlig.
By the AGL naming rules, rperiodsuperior would be named r_period.superior
If the Roman numerals are not different from the regular capital letters, then I would remove them from the font. Else, I would name them as alternates, and specify a substition feature to get to them. You are treading new territory, so you can do what you want - just let your users know. Personally, I would specify these as stylistic alternates of the capital letters. e.g
I.romannumeral
V.romannumeral
X.romannumeral
feature salt {
sub I I.romannumeral
sub V V.romannumeral
sub X X..romannumeral
} salt;