J3 Driver
Hello & Welcome to the Forum!

What a wonderful inheritence.
Personally, I would just get a bottle of Meguars Clean & Polish and have at it.
You will be maintaining the set in its original condition, showing the love and play it received over the past 89 years.
It appears to have zinc pest onthe wheels, they will need to be replaced.  I believe fellow Forum Member Bill Hennings
may have replacement wheels available at their shop; Hennings Trains.  If they don"t I am sure they will help you find them.

Value, check the online auction sites completed/sold listings to see what people have paid for them.

Happy Rails!
Dave