You are just kicking up dust with a few suggestions as to why hacking into a Mac might be a little more difficult - everyone has known about Java for... well, forever.
So sure, don't download certain software or click on certain email links or go to an untrusted webpage.
Gee! People do that don't they. Sounds like a good idea for Mac or Windows and sounds like how crap gets into any computer. If you don't do a lot of things you will not pick up malicious crap. I don't and I don't pick any of it up either on my Win 7 64bit OS.
The real issue is that there is simply more crap out there for Windows and virtually nothing for Mac.
And the reason that is? Simple: It really is a lot harder to write successful malware for Macs.