yes you can stack the adapters and do that. 

This is fixed focus. 

Yes, you can use the binoculars while wearing glasses! 

Well, i will answer your question. At first, these binoculars have a short eye relief distance that means you can roll down the eye cup to adjust the distance. If your vision is not too bad, i can make sure you will view things clearly if you use them without your glasses, just focus the left eye with the center focus wheel and use the dioptre setting on the right lense to focus the right eye. Of course, if your vision is too bad, it doesn’t matter if you wear glasses. In fact, you can see more field if you wear glass. Hope this helps. 

Yes, I think so. I've worn my glasses when using these binoculars.