Welcome to the Amiga world from a sort-of fellow newbie.
first things first, even if you don't like soccer, get "Sensible World of Soccer". Just trust me.
Secondly - do a google search for "Big Book of Amiga Hardware" - this will help you with any hardware thoughts/questions for the A3000 - or for any Amiga really.
Some miggys use SCSI, some use IDE, it's possible for both to be on there. All I know is that if you run a hard drive and want to boot off it, make sure you have a proper kickstart ROM in there - some check to boot too fast before the HDD can fully spin up. Might make you think it's a bad drive when really the KS is just speedy.
Hope some of this helps, and enjoy that beast!