Switching substrate on the fly.

Hi,

I'm wanting to change my crushed coral substrate to a DSB as one step in
a slow migration of my FOWLR to a reef. (46 gal bowfront)

So my question is, will taking out the crushed coral destroy my
biological filter and I have to recycle the tank? I have an Emperor 400
with biowheels as my primary biofilter. So as long as thats unharmed,
can I put my fish back in as soon as the sand has settled and water
cleared? (I have some liverock, but not enough for filter. prob 15lbs)

and whats the best thing to do to with my biowheels to save the bacteria
culture while they're on downtime during the switch? Leave them in the
filter (air, no water), or submerge them in tank water (water, no air)?

its gonna be a big enough headache getting my tang outta that tank for
the change. I'm hoping she can just hang out in a bucket during the
change. What's the total predicted time one might expect such a switch
to take? In other words, will the fish need to be housed elsewhere for
a few hours, overnight, or several days/weeks?

TIA
Phil