1-3. You're correct on all items
4. Potential
5. Exactly equivalent to だろう or でしょう. It is just written in the である style instead of the です style, which is very very common in literary works. Flip through some of your books and you should quickly notice that. The で is quite simply merely the adjectival な conjugated to join the two adjectives.
Please tell us you were smoking dope when you thought it would be a good idea to use Google Translate.
The second one I think literally means "magical [world of uniqueness]". Is that right?
I don't understand the first one at all really. I'm guessing it might be "world of [magical uniqueness]", but is で some form of the copula? Is 幻想的で独特 a unit of meaning? Why is it not 幻想的な独特? Or could で have a sense of "because" (i.e. it is unique because it is magical)? As you can see, I am clutching at straws...
独特 is a bit special adjective. It can take both な and の in the adnominal form, just like わずか, 特別 or さまざま. Unlike 自由, 健康 or 親切, there's no difference in the meaning between the two forms, i.e., you can also say 幻想的で独特な世界 or even 独特で幻想的な世界.
OK, so, in 幻想的で独特の世界, do 幻想的(で) and 独特(の) both adjectivally modify 世界, and we use で in the first instance as a sort of "linking" form because there is another adjective following?