I am new to Dahons so don't have too much real experience but have been reading up on it recently so will pass on some of what I have picked up.

Firstly you need to decide what you are going to use the bike for. It sounds as if you are trying to replicate the position and performance of your road bike on the Dahon. This is only necessary if your usage of both bikes is going to be the same. For example, perhaps extending the reach a little would be ok and easier to do than matching your road bike exactly, ditto gearing.

If you really do want a folding road bike then perhaps a different bike might be better? I think the Swift folders are easier to get a full bike position. Or a Dahon with Dualdrive rear wheel would give you full gear range without a front derailleur.

From reading these boards it seems that http://www.thorusa.com/ is the best source there for bits.

This is a blog by someone in Singapore who has detailed lots of upgrades to a Boardwalk including many of the things you want to do http://handsonbike.blogspot.co.uk/ Check on the right hand sidebar for the list of Boardwalk articles.

I think Dahon have used the Boardwalk name for several versions so it may be a good idea if you put up a photo.