Most fo the characters were taken from Caroline in the City (official site), but their personalities or past don't actually have incluence on Your journey. Also any knowledge about series episodes aren't needed. But just for the record You should be aware of some informations about them that will help You:

Caroline Duffy - a successful cartoonist from New York. She was born in small town Peshtigo in Wisconsin, but she moved to NY to start a career as author of comic strip "Caroline in the City". In the comedy series Caroline was played by Lea Thompson (more info).

Annie Spadaro - friend of Caroline, she lives in apartment across the hall from Caroline's. Annie is an actress, she is in musical "Cats" for years. In Caroline in the City Annie was played by Amy Pietz.

Richard Karinsky - Caroline's assistant and a struggling artist. Always depressed because his career as painter isn't working as he was expecting it would. In the comedy series Richard was played by Malcolm Gets.

Del Cassidy - he was engaged to Caroline, but they never got married. Del is owner of Eagle Greeting Cards, company that sales some of the Caroline's work. In the comedy series Del was played by Eric Lutes.

Charlie - he works with Del in Eagle Greeting Cards.

Remo - Italian owner of Caroline's favorite restaurant called "Remo's".

Jeannie - former Caroline's assistant before she moved out of New York to ger merried and Richard had to takeover her job.

Tim Walters - owner of electronic company in Atlanta. Caroline is engaged to him and they are getting married soon.

Salty - Caroline's cat. Doesn't speak much... In the comedy series Salty was played by... a cat.