For finding a ceiling joist, you mentioned a track light. There is a good chance the junction box is attached to the joist. If you can easily pull the light down and look in the box, you can find the joist and orientation. They should be spaced 16" apart.
I don't think the projector will be in the way unless you go with the long mount. I went with this one:
https://www.amazon.ca/VIVO-Universal...dp/B01013QA86/
I was able to remove one articulation section(it's not perfectly removable, but I did get it secure) to reduce the total length a bit because my ceilings are under 8 ft in the basement, and the extra articulation seemed pointless. They all have a bit off vertical offset.
Also, if the top of the screen is only 3" below the ceiling, you will want your projector as close to the ceiling as possible. Yours looks to have 1" offset at that distance, so you really want the centre of your lens is 4" below the ceiling. Mine is about 6" even with that mount. So you will have to tilt the projector a bit and use keystone adjustment to keep your mage square. It's not ideal, because pixels get remapped, but it isn't a deal breaker. With the long mount it might even be beyond the range of adjustment.