Yo! We've got the first one!
1. Do you have any estimate of how much RAM is needed to load up the unchanged WN3 dictionary?
Crude estimate (e.g. ...freeMemory() before and after dictionary.edit(), which caches everything in memory) for FileBackedDictionary: 55428440 bytes -> ~53Mb. for MapBackedDictionary: 47091144 bytes -> ~45Mb.