Well... those are the answers you don't want to hear. Ahhh you already knew it though or ya wouldn't have asked. And good for you, we've all been there.
IDK..? I just always like it clear, that tells me I'm good. Sometimes you get a bad pc. of glass. I explain it off that the "Cat pissed on it."
Always work the top down.
Are you adding cabosil to the PB?
https://www.amazon.com/Fasco-Epoxies-Cabosil-Silica-Thickener/dp/B0756L83XR
You will find poxy will flow downhill so may need to keep working it.
Any number of ways to do it properly. Solder, crimping {many types to use. Cover with shrink tube, done.
Marine grade wire is suggested and is copper strands coated or called "Tinned". Recommended...