1. Throw away the new empty Library and put the transferred one into the PIctures Folder. Then Hold down the option (or alt) key key and launch iPhoto. From the resulting menu select 'Choose Library'
NOTE: there is no importing involved here. Just moving into place and starting iPhoto.
2. What does "slightly odd" mean? Note that there are changes between iPhoto 08 and later, and iPhoto 1 and 6, in particular how the files are accessed. For help accessing your photos in iPhoto see this user tip:
I tried to get at what I meant by "slightly odd" in question B with the iTunes example: when I dragged old music to my mac when it was new, my old files were stored in an "iTunes Music" folder but because iTunes had been updated, I ended up having to put them im the "Music" folder inside "iTunes Media".
Likewise I was wondering if it would need to sort the photos in iPhoto in a different manner that would require something of me. But I was thinking of the older iPhoto libraries that actually let you see individual folders for each year if you double-clicked on "IPhoto Library" in the Pictures folder.
These days I guess if you double click on the iPhoto Library it just opens the application, so it doesn't matter.