If they are as rusty as you say, a nice bottle of PB Blaster will come in handy.
Also, as with the brake lines, the right tool can make all the difference. There are wrenches made specially for line fittings. They go by many names. They can be called "flare wrenches" or "line wrenches" and there is also a version in socket form known as "crows feet".
Here is basically what they look like:
As you can see there is a small section removed so that the line can pass through and then you can get the socket onto the fitting, this is much better than using a crescent wrench or vice grips, and can make all the difference when removing a rusted fitting, especially considering they are usually made of soft metals.
I will warn you they are pretty pricey, I picked up a set of the crow's feet sockets at harbor freight for pretty cheap, and have been pleased so far with them. It is possible to buy a set of box end wrenches and make your own by cutting out a small section of the wall....safety glasses!
Thats about as much advice as I can offer on the mechanical side of things, Im pretty sure you can buy fuel line, I know you can buy brake line in various sizes and they really shouldnt be much different. In fact if you can get the right fittings, Id say go ahead and use brake line. Brake lines are built to handle much more pressure than an electric fuel pump puts out, and brake fluid is much more corrosive than gasoline, so why not?
Also the only thing that comes to mind for rust prevention would be to paint/coat the lines in some sort of rust preventor, this would be really tedious, but im sure its possible. The ones you have now have lasted 10 years with no treatment whatsover, and probably not being cleaned like they should...do you expect to still have your Intrigue in another 10?