I've found that it is pointless to do a fishless cycle (ish) once you have an established tank. When you buy/receive the filter for the new tank, run it on the old tank for a few days-a week, and you'll be able to add fish by the end of that period. If you have two identical tanks, you can swap filters earlier, and probably avoid a mini cycle if your established tank isn't overstocked.
As for additives, I would like to see a side by side comparison between a "cycle" product and just a normal fishless cycle. I'd expect the times to be pretty close to within a few days of eachother (leaving out biospira, because that has been proven to work, if the lfs takes care of it and it's not expired).
For ammonia, I think the two ingredients should be like ammonium hydroxide and water (the one I have has a chelating agent, and I think that was fine).