I remember reading an article on landing a while ago that was descrbing the ground smacking event you are describing. If I recall correctly, one of the reasons cited in the article is that the wind speed near the ground can be significantly lower than a little further up. When your plane suddenly reaches this calmer layer of air, there's a sudden loss of air speed so it drops faster. Does this happen to you on calm days, or perhaps just windy ones?

I have some idea what you're going through with depth perception. My right eye has a severe astigmatism. When it first developed, 15-20 years ago, my brain ended up adjusting for it by changing me to be left eyed. Since I'm right handed, this makes shooting a bit challenging. Anyway, I have a contact lense that corrects it some, but it's far from great. For flying and boat racing, I've learned to use background objects for orientation. As opjose said, find some reference points you can use to line up to the runway. If there are no good objects to sight, ask the club if you can put some low flags at the end corners of the runway, or even past the end of the runway to help you line up.