1. Regardless of the structure, the offer needs to be competitive. This wouldn't really help with lowballing offers.
2. Across the ~30 offers I've given out, I don't think that either of the 3 variants is more common. I suppose that indicates that different candidates are indeed optimizing for different situations.
3. Our hiring has intentionally skewed more senior and I think the variants of offers has helped create more family friendly offers.
Regarding options, I tend to make sure to offer to spend a good bit of time laying out the details of how they work (strike price, preferred value, vesting, cliffs, early exercise, etc.). They are indeed confusing and I find that people typically either overvalue the value of the options today, or undervalue the potential upside.