Yes - the Recovery disks will work on any HD (although depending on the manufacturer you may have some work to do with partitioning the diak afterwards, as it may use a fixed partition size for the system/boot partition).

Yes, an image of your current system is always a good backup - so long as it is stored away from the machine so that physical damage to the HD doesn't trash the backup as well. You should test the image as well, to be sure that it works!