Question about floppy disks

[Hyperspeed]

Someone mentioned on another thread that WinXP won't allow you to format a Double Density/720k and since they only sell High Density in shops I'm wondering if re-using the 20yr old stuff is safe.

Don't the magnetic surfaces degrade?

I kinda like the vanilla Amiga branded Maxell disks that came in the A1200 packs.

[Hyperspeed]

Maybe it's a good idea to get one of those floppy drive cleaning diskettes with the fabric thing inside. You put a few drops of the supplied fluid on the exposed bit and use a program such as the hilariously named Scrubber:
ftp://de.aminet.net/pub/aminet/disk/misc/scrubber13.lha

This will move the drive head over the fabric disk to give it a good clean.

They say that deposits can build up over time on the drive head, especially if you smoke (this was a problem with Playstation laser lenses).

I'm just wondering though if floppies with read/write errors can be 'cured' with a Full Format. Does this re-align the magnetic particles?