Can the adverb "daily" be substituted here ?
Is щодня synonymous with кожен день? Or does кожен день carry a different connotation?
Yes, they are. "Що" here basically means "every". And it's not just about day, you can also say щохвилини, щороку, щопонеділка, щоранку, щомиті, щодоби. These "що" variants are considered more traditional for Ukrainian language
My dictionaries aren't finding щомиті and щодоби. What do they mean?
мить means "moment", щомиті = every moment. Доба — 24 hours
Why does "My female friend reads every day" not fit?