This was the one I was bad at too; fortunately, I got the rest done in enough time to (I think) get most of it.
Not sure of my particular answers to each question, but I do remember most of them.
The first (it was question #13) was the correct order one; I might have gotten D (not sure of which, to be honest)?
The second I don't remember well; your description sounds accurate from what I remember, though.
The third was about what places Gallagher could inhabit. I'm almost certain it was second and fifth; I believe it was stated Gallagher couldn't be third, and first and fourth were reserved for areas discovered in a previous century than the second (tenth was the last century available to visit, and Gallagher's was set at tenth by the clues).
The last was how many lands visited could have been discovered by Ferrera; I put four, but I wasn't certain (I had it narrowed to three or four, since Gallagher had to be one; based on the conditions, I couldn't find justification for having to include the O one, since I thought you could set Gallagher at second and then have Ferrera as the rest).
I believe the one I'm leaving out was about the O explorer whose name I don't recall - I think it had something to do with the condition that he couldn't be visited fourth or fifth. Hope this helps, and any help piecing together details would be appreciated if my ramble jogs a memory for anyone
edit : for clarity's sake, it was Ferrara, Gallagher, and the person whose name began with O; the centuries were 8th, 9th, and 10th. There were conditions that Gallagher had exactly one on the list, and it was discovered in the tenth century; the O explorer couldn't be fourth or fifth; any lands discovered in the eigth century were discovered by O; and the third land visited had to have been discovered at a later date than the first and fourth. There may have been one other condition I'm not recalling.