For rookie hitters, Joey Votto has a great chance. He'll likely be starting on opening day and he has a legit chance to hit .300 with 20 HRs and 10 steals. Playing in that tiny ballpark of his, 30 homers wouldn't surprise me at all.
For rookie pitchers, Joba is obviously the big name but everyone is already onto him and his value is going to be higher than it should be. Same goes for Clay Buchholz of the Red Sox. If you want a potential steal, try out Ubaldo Jiminez. He has control issues but has worked this offseason to overcome them. He is only 24 and has a few plus pitches. Would not be surprised to see him take another big leap forward. He's going undrafted in most drafts so take a late round flyer.
As far as the Japanese go, the pitchers this year don't impress me at all. There are two closers coming over but I don't think either of them is good enough to make a serious dent in fantasy ball.
Fukudome is the only hitter I see making an impact from Japan this season. The guy knows how to get on base and will hit for a nice average with some power. Something along the lines of .308, 23 HRs, 6 steals, 90 runs and 90 RBIs. Very good hitter who can definitely help a fantasy team.