Welcome to you both.
17hours have tri suits that are a good price. Family business. https://www.facebook.com/awesomelookingtriathlonclothing/ Facebook message them (Wayne) with any questions. Tell him Cranky sent ya 😉
As for training, you can grab a free beginner program online if you want something specific to follow. I don't like to think, so I'm happy to just follow something. Just google "beginner triathlon training plans" or something like that and you'll get heaps. Once you get more serious, you can subscribe to TrainerRoad or Training Peaks (discounted with a Triathlon Australia membership) and they have online programs. I like TrainerRoad because, even though they specialise in cycle training, they do combined swim, bike and run programs for all the different triathlon distances and give you options of low, medium or high volume programs (depending how much time you have available to you). If you're interesting in going this way (TrainerRoad), let me know your email address and I'll send you a free one month trial (when you're subscribed they send you these occasionally to hand out to your friends).
Nutrition - as the others have said, when you're doing short ones, don't stress too much, but when you extend your distances out, contact Jason at Infinite Nutrition Australia and he'll be able to get you sorted with either a standard or personalised mix, and will take all the thinking out of it for you. Again...I like this! Also you'll get a discount if you drop the "Transitions" name. https://www.infinitnutrition.com.au/
Wetsuits are generally only allowed if water temp is below 22°c. Don't worry about a speed suit until you're racing at the pointy end of your age group. They are expensive, but you might find a second hand one on Facebook's Triathlon Marketplace when you get to that point.
Welcome aboard. This place is awesome and a wealth of knowledge ... just don't take anything personally if someone has a dig. There are some great people on here, so just focus on the positive comments and ignore the others.