Yes. It’s compatible with iPhone 12 

Yes so far all my connections with apps work. I have iphone and i use the hdmi iphone adapter and am able to play. Hulu, disney+, youtube, netflix and even an anime app i use. This projector is the best one ive used. Only sucky part is if you have kids: they will guarentee take this from you and perminatly set it up in their room 

This is a recorder and it's not wifi enabled. To view on a phone the SD card with content must be inserted. 

Yes, it is adjustable to all phone sizes from what I can tell. 

The adapter will mount the lens and you will be able to use it manually. However, my copy of the adapter does not allow the lens to be fully mounted all the way until it clicks into place. It doesn't quite make it, but it's still very solidly mounted. Also, the manual aperture linkage doesn't work properly (on my copy, at least) so exposure is controlled only by shutter speed and/or ISO. You will be able to manually focus and zoom the lens but no VR, of course. It will be a frustrating experience. Instead, get a 14-140 Panasonic zoom if you can afford it!