[Gambo]

Before I answer the questions. The .odb database is the .csv files merged together for quicker access. Essentially it is somewhere between a .zip (.rar) file and an access database. There is no difference in data between the .odb and the .csv file.

1) Yes. The .odb is the lahman database with adjustments made by OOTP developers to make it more accurate. It contains both the real stats and neutralized stats within it. It can be used to any style.

2) Yes and No.
a) I'm not certain what the garlon db contains but the Gambo database has all the same data as the .odb with minor league seasons, negro leaguers and some minor leaguers added in. So yes the data will be there.
b) The provided master.csv file (which is the same file included in the .odb file) provided in game does have pitch and fielding ratings. My database uses an adjusted master.csv file based on the provided master.csv for this year so it does include the same ratings the .odb and the original .csv includes. BUT...
IMPORTANT : the "real" pitch ratings don't exist yet and no matter what database you use it will not import the individual pitch ratings. This function does not exist yet in OOTPX as it was not completed upon release. So no matter what database you use Phil Niekro will not throw a knuckler. The game will always produce fictional pitch ratings.

So the answer to your final question is I really don't think it makes a difference. I just imported 1907 using my database (.csv) and the .odb database. In mine for Waddell he had 3 pitches rated 6-6-6 and the league had very few higher than that with the max at 8. When I did the .odb database he had 3 pitches rated 8-7-6 and he actually had the only pitches rated above 6.