As I understand it, nobody was tapping Flynn's phone.
Exactly. The FBI says no problem with their interview of Flynn. His sin was within the admin and whatever went on between him and Pence.
The recordings are SOP and happened under the Obama admin. The release of the info was criminal on a number of levels.
Flynn was dumped by the Obama admin because he disagreed with the with the admin on it's handling of terrorism and on the Iran deal. The Iran thing Obama considers a legacy issue. It is not unreasonable to think there are those from the prior admin who wanted to take him out so that he could not help dismantle the Iran deal. He's been in intel a very long time and probably knows where bodies are buried.