JavaFX and Rules Engine

I am looking for a more nimble alternative to a legacy Swing application which has many screens with lots of controls on each. These controls are simple: text boxes, check boxes and buttons. It's a client side application that communicates to a server. Almost certainly, I'd need both Java and JavaFX to coexist on client. I have two questions:

1. Would JavaFX be a good alternative? If not, what other alternatives do I have presuming it won't be a thin client

2. How convenient would it be for the UI to be validated using a rule engine which will need to be on Java side - I think?

I don't know JavaFX yet and am considering if I should delve into it.

Thanks in advance.

To answer your first question-
JavaFX 2.0 has lot of changes from its previous versions- new rendering engine, new UI toolkit and whole lot of new components and also lot of performance updates. And the good thing is that it can coexist with the Java application, in other words JavaFX is just a Java API.
So I think JavaFX would be a good option.

Learning JavaFX is nothing but learning another Java API. Though there are a lot of new things in the API to support the binding behavior which was present in pre 2.0 versions.