Can it be wore on the pinky toe?

No, it’s meant for the second toes for hammer toes. There’s others out there for pinky toes.

They are too long, Can I cut them to fit?

Yes, they are easy to cut to fit and the elastic is adjustable

Is this the best Bunion Pads brand? quality guaranteed?

This item is for Hammer Toes. The question above is about Bunion Pads. Maybe you can find a Bunion Pad buyer to answer the question.

What do you do with the extra material from the strap on back side of Toe Straightener?

Ya' know, it just hangs there. These work for a while, then you have to re-thread them, (because they come out) but they're worth a try; we all have different issues, (they eventually break down) and we're not going to train our toes at later stages of our lives. I just wear Big Toe dividers mostly these days., keeping those from crowding-out the others. I have Hammer Toes, my Big Toes want to make left & right turns, my 3 little ones are curving toward the others, the VA screwed up the one operation I had; second toe is sticking upward, the Big Toe is making less of a turn, but should of been made straighter. Good luck w/ whatever you have going on...