[Grml] udev rule for usb boot device

What is the best/approved udev rule for a usb hard drive to escape random drive letter variations /dev/sd[a|b|c|d]. The drives have ATTRS{serial} but I want to walk carefully amidst grml's built-in rules. For example, if sandwiched between other grml rules, what lexical filename to use.

Second question: will the udev name work from /etc/fstab during boot, or should we stick to mount-by-label.

(Idea for grml2hd - use hostname to auto-generate a related udev naming rule for the drive.)