Ok.. here is where I think you need to start.
Ask yourself if you want the hood and engine cover to open up like the original (look at pictures on the internet) or do you want them to open another way. Having them open in the more original fashion is more work, but it's up to you how important this is. I'm personally going for the more original look on my roadster so I'm using a VW Jetta hinge for the hood up front and I'm using a bearing block in the back (will be mounted under the rear humps) with bent tubular bars for the rear. If you are planning on using one of the new inner hood panels, they will have the OEM hinge and latch mounting sections molded into the part so this might force you to go with the original opening method anyhow. The trick to mounting a roadster engine cover is to slot and install your hinges in the rear quarter panel humps and lift the cover up from the outsides of the engine cover. You also need to think about your spoiler panel and if you are going to hinge it to access any trunk space or install the panel in place like the original. I'm installing mine in place but it'll easily be removed by taking out a couple of pins.
Here are some pictures that will hopefully help you:
Picture 1 - Jetta hinge for the front hood.
Picture 2 - Custom center lift front hood hinge
Picture 3 - OEM roadster engine cover hinge
Picture 4 - Dratts roadster engine cover hinge
Picture 5 - Bearing block that will mounted under my quarter humps and attached to a tubular strut that will lift up on the outer edges of the cover.
Chris