Language / Polish Nickname - Mikołaj = Miko? Elżbieta, Wiktoria [14]

Word like 'nutkja' doesn't exist in polish language. Maybe you meant 'nutka', a diminutive of word 'nuta', whitch means 'tune/melody'. But it also can be a short form of feminine names like e.g.: Danuta (Danuta -> Danutka), Anna (Anna->Anutka).

Language / Naming / Nicknames for Aleksandra or Alexandra? [24]

No, we don't use this diminutive. It's a russian form of this name.

Language / Naming / Nicknames for Aleksandra or Alexandra? [24]

Name like 'Aleksandrina' doesn't exist in Polish. But nicknames for 'Aleksandra' are: Ola (the most popular one), Olka, Oleńka, Olka, Aleks (less popular one).