I use TMPGEnc-Author. How you proceed really depends on the nature of the discs. RAM uses DVD-VR format, and many programs do not play nice with VR. If the discs have just one recording session on them, then it's simple and you can use any software. Just re-name the "VRO" file to "MPG", and import it into any authoring program. If a disc has multiple sessions on it, then you must use a program that can fully import VR discs, like TMPGEnc-Author.
If you used a high-bit rate recording setting on the Panasonic, you will be able to put maybe 3 hours onto one DVD by shrinking the final project to fit. If you used a lower bit rate recording setting, it won't shrink well at all.
So author your new DVD with as many of the recordings on it as you like, create a menu, and away you go. And get a big-assed hard drive to store the ripped recordings on till you're sure you have the output you want.
Avoid programs that will re-encode the video, as this will always result in some loss of quality. TMPGEnc will not re-encode, and if you need to shrink the project, DVDShrink is the ticket.