A:AnswerYes, it does include the AM4 bracket. I am currently using this in my latest Ryzen build. I would recommend swapping the fans out though. The fans that came with it are a bit loud.
A:AnswerIt depends on your case. As long as you have room for 2 140mm fans (280 mm) and there is enough room in the top of the case not to interfere with anything on the mobile. Most likely if you have room for a 280mm, you'll be fine.
A:AnswerIt should but it also depends if your case will support the radiator itself. If your case will support the 280mm Radiator then you should be fine. Mine did come with an AM3(+) bracket.
A:AnswerYes, it will work, but not as efficiently. You'd probably have to run the one fan harder. You may also need to mount the other fan somewhere so the sensors are happy.
A:AnswerYou probably already found the answer so this is for future customers. Yes this works. AM4 and AM3 use the same cpu bracket. So as long as the board has the AMD lockdown points it should work with the included AM3 bracket.