It is not in the Scrabble dictionary, nor Webster's Second International, nor the OED. It doesn't seem to be a word at all, so I would guess not.
No. Ci is not a Scrabble word.
No. Eariest is not an acceptable Scrabble word.
No. Wop is not an acceptable Scrabble word.
No. Fo is not an acceptable Scrabble word.
Yes. Moot is an acceptable Scrabble word.
Yes, "nus" is an acceptable word in Scrabble.
No. Excelsis is not an acceptable Scrabble word.
Abbreviations are not acceptable in Scrabble.
No. Viz is not an acceptable Scrabble word.
No. Cie is not an acceptable Scrabble word.
In my eyes yes RN is an acceptable scrabble word.
Yes. Jo is an acceptable Scrabble word.
Yes. Re is an acceptable Scrabble word.