1) These look like the blank thick pbt keycaps that imsto used to sell. It's currently out of stock.
2) It's not ISO layout, it's just ANSI layout without the two windows keys and the one text key. Not sure if ther's a specific name for that layout.
3) It's called stepped caps lock.
4) You can send a PM to imsto, but he told me it's out of stock just a few days ago. I'm not familiar with that RGB set, they seem like OEM profile,it's probably Keycool's product like this:
http://item.taobao.com/item.htm?spm=a230r.1.14.11.C5YV7q&id=18673231029The same RGB set was also sold by Leopold which is a Korean keyboard company, and Keycool used to be Leopold's OEM, not sure if it still is.