Thanks EulerFan.
One more thing about the first question. If the equation was set up in a way such that there was only one of those sulphur molecules in the equation, this means that it can't undergo both reduction and oxidation right? Because there's only one molecule of that type, instead of 2?
Firstly, I think you're missing the link between the theory and the practical. You're trying to describe a chemical reaction in which there's only one sulphur containing molecule. As someone who regularly images single molecules, good luck trying to do a reaction with only one of the sulphur containing molecules. Imagine this - you have your beakers set up, one is just water, the other is a salt of S2O4^2-. Now, your mission is this - take our your tweezers, pick up only a single molecule of S2O4^2-, and place it into the water. You can't tip the second beaker into the first - even if you only had a gram of your salt, you'd still have 0.01 moles of the anion, and that's 6.02*10^21 molecules! It's absolutely insane, and not really feasible.
tl;dr - your question isn't really appropriate. Try and look past the theory and into the practical that it represents. Remember - chemistry is a PHYSICAL science, so you should be able to picture some physicality to it at all times.
Secondly, I don't think it's impossible that a single molecule could be reduced and oxidised at the same time (essentially, for the molecule to oxidise itself, such that one functional group gets oxidised by another, with the oxidising group thus getting reduced). Probably beyond VCE level, can't find an example, but in my mind I don't see why such a molecule can't exist.
One question here if anyone is keen on reading my working, http://m.imgur.com/a/lh829
The answer wasn't provided and my answer doesn't sound that good..
There's not really much to say to this type of a question - nobody's going to ask this. It doesn't really test chemistry, it only tests if you kind of understand what's going on. Tbh, if VCAA wanted to ask something like this, they're more likely to ask something like, "what would happen if sodium chloride was used instead of hydrochloric acid? Would the same stoichiometric amounts be required?"
Your answer suggests you've got the basic gist of why things need to be balanced, so I wouldn't worry about it.