Kutastha

There's no need for that. Set aside some time to practice yoga in the morning and evening or just once per day if you don't have time for two sessions.During the day you can keep your mind focused on breathing when you don't need it to preform other tasks. Pranayama affects subtle inner currents(vayu) and it can cause health and current flow issues if done incorrectly or excessively. That is one of the reasons why kriya should not be practiced by merely reading various books and without supervision of a person who is authorized by his teacher to teach kriya. Or at least a senior, experienced kriyaban(person who practice kriya is called kriyaban). For example, if you need some complicated electrical work to be done and you don't know what you're doing when it comes to electricity, you'd call a qualified electrician or at least ask someone with a lot of experience for an advise. Or otherwise you should be ready to face possible consequences of messing with the electric current. The same goes for practicing yoga. And by yoga I mean stuff that comes after asana, according to Patanjali.

Many did it. If you're looking for the proof of efficiency of kriya, then the proof is in the pudding. Also it is in the fact that it's an unbroken tradition of teacher-disciple succession (guru-shishya parampara) for the last 160-ish years.That's since it was reintroduced to the public by Lahiri Baba as instructed to him by his gurudev, Babaji Maharaj. It survived the test of time, if it was a bunch of mambo-jumbo people would drop it long time ago.

Generally if they ask for more than a symbolic amount of money for diksha ie. initiation, run away. Acharya's ie. teacher's intention shouldn't be on money but rather on helping you.