*sigh*
1) If it is an ISO I have huge doubts that this is legitime, true Mac people use .dmg's rather than ISOs. There have been a lot of cases recently of people downloading MacOS X versions from sites like this and finding that someone has slipped malware in the image (really easy to do actually). It is worth the money to get yourself a legal, valid copy.
2) It is philosophically worth buying MacOS X. You are directly supporting the development of something you are already demonstrating has value to you. The salaries of the engineers and QA folks that make MacOS X what it is don't come from nowhere. If you want people to pay you for your work, pay others for theirs when you value it (and literally you are valuing it).
3) When you mount a virtual partition, and then reboot, durring the shutdown the virtual partition (the ISO) is unmounted. There are tricks to do a fake netboot against a dmg, but since you have an ISO, and don't have access to the needed tools, you are stuck needing an actual partition (like a dual-layer DVD or a HD partition) to boot from.
From there there are even more tricks, but I think you need to go back and correct some basic problems in your thinking on this subject.