Haven't seen the e-mail yet but as soon as I do I'll forward you the info.

If you are talking about the rubber hose to the pressure regulator then you can replace it with typical rubber hose. That line frequently cracks but it carries no pressure so standard rubber line, such as type used for vacuum lines, can be used. If it's any of the high pressure fuel lines the thickness of the line will be obvious and you'll need lines rated for fuel injection service.

Yes, replace the fuel filter. I would also suggest pulling the entire fuel rail and getting the injectors cleaned and flow tested. Sounds like you have the problem narrowed down.