Pretty sure these are two separate problems, with a shared cause: bright light. The first problem is a light leak. The second problem is... Well, a little more complicated. I occasionally fix LC-As, and I remember one time I had one that worked absolutely fine when I was testing it at my desk, but then when I went out in the daylight to shoot a test roll, it would look like your film: blank, with the occasional ghost of an image, and a few normal images. It turns out that the camera was fine in low light, or rather below a certain threshold. Above a certain brightness, the shutter would fire but the aperture blades would not fully open, and would just "twitch", leaving a blank frame (they would sometimes just about manage to twitch enough to let a tiny bit of light through, hence the very faint images). I never did manage to fix the problem, sold the camera as spares.

It looks like this is happening with your camera. You mention the film was 400 and shot in bright light, which makes sense if it is the problem I described. If it was for example 100 shot indoors, I think you would have seen many more good frames on the roll. You can test this yourself: set the ISO to 100, indoors, fairly dim room, open the back, wind and fire. You should see the aperture blades open up fully to 2.8, and stay open for a second or two. Then wind on, set the aperture to 400 and point the camera at a lamp, wind and fire. You should see the blades twitch, but never open.

Oh and the reason the two problems coincide is probably the light: if the camera is used in bright sunlight, the shutter problem will manifest and the light leak will let more light in, making visible leaks in the film. In darker conditions, the shutter problem will not manifest, you will get a normal photo, and there will not be enough light to leak through and show up on the film.

Hope this helps, please try the above and let us know if that was the problem.