apart from spud (jst haven't gotten round to it) we've grown all those vegies nae - we basically blocked out a part of our yard (pretty much full sun) planted, and kept watering it every couple of days... success with all of them. easy! we have used soil from thorpy - not sure if your soil is the yummy red stuff up where you are - but it's fantastic for growing the vegies!

passionfruit you need to have two vines (male and female) and they are climbers so you have to accommodate that (fence or wall to grow on - pretty simple low maintenance). rockmelon/canteloupe we grew in our normal vegie patch - high water needs, and we just let them "climb" over the side of the vegie patch as they spread out heaps. letting them hang down over the edge of raised garden beds meant they had more room and the actual fruit weren't sitting in mud or anything

fruit trees are pretty low maintenancy. nectarines are self polinating and you pick up the plants in big w or bunnings, and most nurseries, during winter. apples - you need a plant to cross polinate with - so most apples need at least two varieties. you can get hybrid plants that have been created to have parts of both fruit on the one plant. these are good if you have space restrictions but if you'll eat or cook the apples two plants is better. you may need to net the fruit trees spring and summer til fruit comes out to keep the mongrel birds off!!! citrus plants are pretty straight forward - plant and forget!

not sure if you can get to any cheap nurseries, but the "hello hello" mob had all these fruit trees and more for less than $20 each last year...