Also with the 1000 amps thing that will blow the hell out of the fuse, as long as the voltage is <= fuse rating, you're good.
For example a 250v fuse means "if it blows it will block <= 250v (absolute)" - if you put say 2.5kv there that'd just arc the gap and it's possible the fuse is no longer a fuse and conducting quite happily.
So with the 1000 amp thing - this example presents no problem AS LONG AS the voltage rating is within that of the fuse.
You are wrong, where are you getting this from?
Look at the fuse safety standards, UL 248 the test jig is set up "short circuit current in rms symmetrical amperes equal to the interrupting rating of the fuse to be tested."
Typical lowest rating is 10kA and they do test to that high current (bigger fuses to 200kA), with series inductors, inducing an arc inside the fuse to 3kV. It's all about taking the arc.
The source test voltage I think is the fuse's RMS rating, so 1,000VAC.
"The fuse shall operate and permanently clear the circuit without damage to the components of the complete fuse within the following parameters:
a) there shall be no re-establishment of current. If evidence of a tendency to restrike is noted, application of the recovery voltage shall be continued for 60 s past the time of restrike;
b) the fuse shall not emit molten metal;
c) no external soldered connections shall melt;
d) the fuse shall not exhibit movement nor deformation of either or both end caps that would result in more than 3.2 mm (0.125 in) increase in overall length;
e) there shall be no holes in the fuse as a result of this test;
f) the fuse body may discolor but shall be readily identifiable for replacement purposes;
g) for fuses with glass or ceramic bodies, cracking of the body is permissible provided that the fuse remains in one piece, without loss of filler, prior to removal from the holder or test rig; and
h) for the threshold test, fuses shall clear in the first half cycle after closing."