[sdiy] transformers and power supplies, etc... for newbie

[Tim J]

Ok, so I need to learn a bit about transformers and power supplies.  Anyone 
know of any good online resources?

I recently bought acquired an old korg micropreset synth.  Its in perfect 
shape (even came with a hard shell case).  Unfortunately its 220v and I'm in 
the US.  The fuse was also missing when I got it.  To get her running I 
guess I need a step up transformer.  Do most transformers have taps for 110 
and 220 volts?  There seem to be at least one unused tap on this 
transformer.
Also, can anyone test me how to test this transformer to find out if its set 
up for us or european voltage?

Lastly,  since nobody in my neck of the woods has a .2V fuse would using a 
.25v fuse cause much of a problem?  I realize using a higher rated fuse 
defeats the purpose of using a fuse but should this small difference cause 
much of a problem?

Thanks,
Tim