Hi Paron,
I'm not sure what you mean by your question "does CF help port the front end over to the Web?" - ColdFusion is basically the front-end AND the application.
If you wanted to use the frontends that you may have in your Access-based applications, you will need to look at the Visual Basic code and SQL, and re-code these into ColdFusion (or even start from scratch and go through the whole application development process again) - there really is no simple way of converting an Access-based application into ColdFusion (or any other web language).
I wouldn't say Access is a better RAD tool than ColdFusion (I wouldn't say Access is a RAD tool at all

- Access is suited for simple desktop applications. ColdFusion is specifically designed for web-applications of any level of complexity.
"It must be, to justify the double effort of developing in Access and then again in CF, unless CF makes it really easy to port over."
Well, I'm not putting double effort in. I only use Access to set up tables in order to test my ColdFusion code - I don't develop in Access at all (may god have mercy on my soul if I did)
Something which may be confusing you is the terms database and application (or the way I am using these terms).
My definition of "database" is simply a collection of related data stored in tables, whereas "application" is the interface and functionality. I only ever use the "database" side of Access, never the "application". ColdFusion is the language that provides the "application".
I do hope that I have not confused things further for you - I've re-written this post a number of times now and this is as coherent as I get at the moment (it's about 1:30AM here in Australia, and the caffeine is starting to wear off).