I think you got lots of sound advice on what leggings are VS tights VS hose!
I wear a lot of leggings and tights (sometimes together?!?!) as an extra layer under skirts, dresses and tops in the colder weather here.
I think a good rule of thumb to use as a starting point in figuring out when to wear leggings VS when to wear tights or hose is this:
- Wear leggings underneath shorter tunics, tops and sweaters that cover your bum and have a looser fit.
- Wear tights or hose underneath skirts or dresses that are longer and can be worn with bare legs.
Of course, this is absolutely not always true, but I think it's a good place to start if you're unsure of how to do things!
Personally, I prefer leggings to be at the ankle, like you have in #1, although I'd try to go even a bit longer than that (where you'd have the hem of a skinny jean). I think this is the easiest length legging to wear and the most versatile.
I like the lace tights, but I think they're more for an evening or night out look rather than MOTG. One trick I like to do to make super flashy tights a little less flashy is to layer an opaque coloured tight underneath. This does require you to have a pair of tights other than black for your lace tights though! xD