Basically,all I want to do is to be able to download software from Aminet.
Can I use WB 3.0 for this?Or do I have to upgrade to 3.5/3.9?
3.0 will do. However you might need to upgrade your hardware. More RAM as a minimum (4 MB Fast-RAM at least.)
Or is it possible to download to my Mac and burn it to a CD so I can load it in the A1200 that way?
Yes, it is. Most Amiga CD-ROM drivers are able to read Mac HFS CDs.
Bye,
Thomas