Converting .DSK, .SDK, .DO images to 5.25" floppy; disk compatibility?

[GameWizard2002@juno.com (Jason L.)]

I recently had an Apple //e -- the holy grail of classic computing --
fall into my lap, but it's not of much use right now, since the only
real applications I have are disk images.  I have a
somewhat-more-than-basic knowledge of the system, but I am having
trouble figuring out how to convert disk images to 5.25" floppies. 
I've read many Usenet posts about the concept, but the methods (such
as ones involving null modems) are all very confusing.  Is there any
conceivable way I could connect a DuoDisk to my PC and use some sort
of conversion program?  If not, what should I do?

(Sadly, not one school in my area uses Apple //e's anymore, so I can't
get tech support from there.)

I also need some information as to how I can reformat IBM-formatted
5.25" disks for DOS 3.3 (or ProDOS, whichever has the highest
compatibility.)   And which size is compatible -- 1.2 MB, or 360 KB?