gonna thoroughly enjoy this. And excuse the really long list for the first questions... *yeah, anime/manga, definately one of my uber-specialized interests.*
1) Robotech, Macross Saga, Tengen Toppa Gurren lagann, FLCL, Yu Yu Hakusho, Ninja Scroll, Ghost in the shell (lumping them all together), Mobile suit gundam (ill lump these together as well, though my favorites would probably be Gundam wing, G Gundam, and Gundam 00, and the original.), Guin Saga, Slayers, Bleach, Fullmetal Alchemist, Code Geass, Excell Saga, Full Metal Panic, Elfen Lied, Outlaw star, Cowboy Bebop. Ill cut this list short by far...
2) I personally prefer subs, since the dubs dont really capture the nuances of japanese as well.
3)There are alot of underrated series. Outlaw star is one of them, love the character development, and the characters themselves. Loved the quirks of the series as well as the banned episode. another one I think is underrated is Guin saga. Without spoiling the plot and whatnot, lets just say, the soundtrack = awesome. Why you ask? Nobuo Uematsu made it. Also from what i have heard, the writer for a bunch of the pre- FF7 final fantasy games is the one who wrote the story for the anime, well adapted the original literature to Anime. So far though, it is similar to FF9 in story/story telling.