[The Game]

I am going to let someone else handle #1 as i have had issues as of late to get that to work properly.
Best I could say is start with 2015 quickstart. Go to League Settings - Add new league. mass delete all fictional players. release all quickstart players, you can affiliate all 2015 minors to you new league if you want. Delete MLB. Schedule fantasy draft for released MLB players in your FBL.

To get players from a particular year. Go to league Settings - Options? and look for the database path. Copy the OOTP stats folder html line or whatever it's called using ctrl-c & ctrl-v into that spot. Click random debut & import historical rookies. Set the min & max from the year you want to draft from and rookies only from 1983 will appear in the draft. Oh set draft for November not June and make it big enough so that all players available will be drafted 10 rounds should be more then enough. Probably wont go past 4 rds.

Only way to have 2015 rookies is the way i mentioned above.

You could start a fictional league add the DB path, import historical rookies anmd set it to 2014 and that might work.
i can not think of an easy way to have vets from each year appear in the draft but i know of a work around, though tedious.
When your draft appears delete all fictional players.
Create new league and go to import historical wizard and import the year you want. Release all 1983 players. Manually edit them so they are draft eligible. and they should populate your june or November 2015 and beyound draft. Backup your league often.
If i had time i would test this myself, so update us if it works.