1. Can the lowers be mounted with the brackets both in front of the blades or behind them? YES.
2. I received 4 long screws, 4 shorts. I assume the shorts hold the blades to the brackets. YES
3. I received 4 metal washers, 4 shoulder washers, and 4 nylon washers, but no explanation where the metal nor nylon washers go. I assume on the blades.
You take a bolt, them metal washer, put in bracket (metal washer against bracket). add glass to brackets other side, on the glass side you put rubber/nylon washer, shoulder washer, then the lock nut. Never put a metal washer against plastic/glass.
4. You guys talked about rubber bushings, the white things in the pics. These didn't come with it, so I assume you don't need these now.or should I buy them as well? The instructions said washers but it doesn't say where the nylon ones or the metal ones go.
He added white washers and rubber but you do not have too.
Hope that helps, that is how I would do it, but I do not have those lowers, but made my own.
The above is the mount outside, like the photos.
If you want to mount bracket behind: It would be bolt, metal washer, bracket, glass, rubber washer, metal washer, nut.
My opinion this way would like nicer, but JMO,
mj