I don't know why you waste your time with the A500 hardisk problem if you have an Amiga 600 with hardisk and working fine?
on the other questiosn you can add anysize of hardisk to your A600 using 2.05 or 3.1 however you need a patch for the scsi.device if you wanna make large partitions
I recommend idefix97,also you will need install a new filesystem like SFS or PFS3
but if the disk is only 4gb you will not need patches...make 2 partitions of 2gb each one
that's all
identical patches you will need for the A3000 if the disk is biggest than 4gb
bye, Laser