Huh what health and safety regs??? Sounds weird to me however in Vic you need approval from each local government to operate in their territory (which comes at a cost) so I would go and speak to them as they administer the food regs.
As for power yes almost all markets etc you attend will have a power supply and to keep costs down I wouldnt buy one initially but hire one on a trailer when required. If you find you are constantly shelling out for one go and buy one.
What part of central vic (bendigo maybe)