The MyBUD's are built in South Korea, so they're not the most user friendly. No manual, but you can figure it out. The glasses come with a battery box they connect to. There's a spring clamp for attaching the battery to the bottom of a cell phone. Fine if you do that, but otherwise it's protruding.
Unfortunately my final test is on hold as I'm waiting on a new gimbal after a crash. In the mean time I've set up the future use. I bought a belt clip for $2 from Walmart that allows you to attach a "button" to the battery with 3m adhesion. That button slides into the clip attached to your pants. This will answer how I hold it. There was no real way to attach it to the controller and use a short cable. I then connect mini HDMI from the P3 controller to mini HDMI input on the battery box clipped to my pants. From there the glasses connect to it. The glasses are quite snug, but the negative thing I've read on the glasses is there's no adjustment for pupil distance, so if it's not a match it may not work for you. I found minimal issue for me. Adjustment wise you can adjust the brightness. I connected it to the HDMI on my Amazon Fire and I thought it was good...kind of like a 19-21 inch monitor in front of you (like how it is as I type this on my PC). I bought these instead of the Fat Sharks as I've heard the screen size is smaller and FS cost $150 more. Unfortunately I had no way to try the FS's, so I went with reading the opinions and reviews. I think the Eachine's look awesome for a similar price, but I wanted something less bulky, and the MyBUD's will allow you to look down below it's frame to adjust your tablet on the controller. There's really nothing else out there that works in a similar way for the price. I will give my opinion of them for FPV when I get the replacement gimbal.