The vector library is awesome and is a nice feature to have. However currently it is in list format. The shape of the symbol is not visible correctly. Here I believe the shape is more important than the name of the symbol. so having it in thumbnail form will be a plus. Ability to have it in thumbnails or have the functionality to configure the view similar to the brush preset docker will be a good improvement.
Yes, this is possible.
This should be in 4.0. I think Boud added it. I also added a slider in the view menu so you can change the size of the thumbnails