#1- Great idea! #2-Hmm. Someone did a REALLY nice job on these. For me, the screw top needs to be hidden, My ocd says NO NO! Could do beaded trim, embroidered ribbon, embossed metal strip, strand of pearls wrapped round & round, etc. Beautiful!
Make an Air Freshener; Poke holes in the lid and fill with baking soda and essential oils. great for the auto also just make sure it does not tip over.
41 Easy Things to Do with Mason Jars, a lot of these are generic ideas you have seen, but there are some genius ones thrown in there.