Rescue disks are bootable DVDs or CDs made via the software involved (Windows or the imaging tool) that aid a user in getting his system back up if there is major file corruption in the OS. The Windows repair disk allows key Windows files to be restored from an external source and hopefully can get the system back up and running if it otherwise can't; the image rescue disk is a bootable disk that allows the user to load an image file of his choice from a still-functioning drive or storage medium onto a hard-drive that needs to be fully restored or has been replaced. Booting from a disk merely requires a temporary change in the boot order of the computer's BIOS to boot from the disk before booting from a hard drive. Cloning a drive is just that: a way to copy/clone one drive, including its partitioning, onto another drive in every respect (this is best done with drives that are similarly-sized). In any case, whenever imaging a drive, ALWAYS make the images a full/system image that includes the boot sector, so that a restoration to a brand-new drive will boot properly... this is sometimes a user-selectable setting that needs to be made in some imaging products when creating the image.
My own experience with most browsers is that, if one has the spare storage space, simply copying the user-account's browser profile folder onto backup is a simple and effective way to go, provided that the source files aren't themselves corrupted in some way. With that, you typically only have to copy the folder back to restore browser operation. (All such copying should always be done with the browser off, of course, to avoid file-usage conflicts.) In the case of stand-alone/portable installs (which I prefer), I actually copy the entire browser folder structure to backup, since it normally includes the profile folder therein. In that case, recovery/restoration is almost trivial - simply copy it all back and it's ready to go.
