It usualy takes about a month with mine. But some fish are pregnant longer without any sign of the gravid spot and the temperature of the water and food they are fed also effect the development of the fry - thus altering the length of time before they are dropped. You'll know just before cause, if you look carefuly, the fry's eyes will be clearly visible to the point where you can actualy see the whites of their eyes too - it depends on the color of the mother of course though as sometimes it's more difficult to notice.
They aren't that small and a very fine net should hold them but it depends on just how fine you mean.
It wont matter if you syphon them out if you check the bucket (using a white bucket helps) for the fry and put them back in the tank. Usualy, however, you can quite easily avoid syphoning them out as they are quite visible. I suppose you do water changes once weekly - you'll be surprised at how the fry grow in a week (assuming you do a water change just before they are dropped - but watch the mother doesn't get stressed and aborts!).
By conditioned water you mean de-chlorinated right? That's fine and should have no effect on the fry.
