Tank Cycling

[carsona246]

How much percentage wise of water you take out is going to depend on the amount of ammonia in your tank. If you have .25 ppm's of ammonia in your tank after one day, you may not need to change it at all. If you have 2 ppm's of ammonia in your tank you might want to do a 75% change. It's all dependent on how much toxin's there are in your tank. I personally prefer to keep it under 50% just so I don't have to be super careful about the temperature, because you don't want that to change quickly either. However, there are many people who do 100% waterchanges with fish(primarily breeders) and have no problems.
I love aquatic plants, and have a tank that is filtered by a water bubbler and aquatic plants. A traditional filter is not "needed" to filter a tank, just a little understanding of the nitrogen cycle and plants. Plant do absorb ammonia/nitrate, however one or two plants will not absorb everything in the tank. Most people still need a filter(of some form) to keep ammonia/nitrite to 0. A simple sponge filter will be all you probably need filtration wise, with or without plants.
Moving your frogs while cycling the tank will only be bad if you allow the ammonia/nitrite to stay at high levels. The point of fishless cycling is to allow ammonia/nitrite to stay at high levels to feed the beneficial bacteria quickly. If you keep the frogs in the tank at the same time you will need to do frequent water changes to keep ammonia below 1 ppm(some people say .5) and nitrite below 3 ppm's. This will slow down the cycle, which is why people typically fishless cycle to keep ammonia levels up.
Again, any fish that you have not raised yourself or monitored for a month, that you put into your tank is a potential host for disease. I'm not saying don't buy the fish, but I wouldn't without quarantining. I have no idea on the compatibility of ACF's and guppies.
You will only be able to tell if a tank is cycled by testing the water for ammonia/nitrite/nitrate.