Questions on boots

1. I saw some boots a few inches below my knees.  Would they be difficult to pair with leggings, skirts..?  I mean, would the length of the boots be awkward?
I have short boots and taller ones.
2. Also, would the zippers wear out often?  My boots right now don't have zippers, but I think it would be nice to have zippers (easier to wear).
3. also, if the boots are made of man-made materials, would they be uncomfortable necessarily?  I prefer leather, but they are so much more expensive.

Thanks in advance for your feedback.