a)Yes it does transform audio data into text, provided you have audio data to start with. One good free data base the creators of Kaldi championed and support is called Librispeech which is available here:http://www.openslr.org/12/.
b)Kaldi gives you access to some of the state-of-the-art algorithms for modelling speech acoustic models. This includes deep neural networks, long-short term memory recurrent neural networks, hidden markov models and a variant called subspace Gaussian mixture models. It differs from other well known projects like HTK in terms of its licensing - it is released under the Apache licence and the suite of state-of-the-art algorithms it offers. So it can be modified and adopted for research and commercial use. Additionally, it has supporting scripts or "recipes" for some benchmark data sets like the Switchboard data set and Wall Street Journal read speech data.