One of the other things to consider when thinking about cost effectiveness of your training is that you will have different requirements / a learning style that suits you and that just because one place is cheaper than the other doesn't mean it will be more cost effective or cheaper in the long run. There's plenty of forum posts / topics on the internet for you to google on this, but one thing that you can't under emphasise is the requirement for you to feel comfortable and able to learn effectively with your instructor and chosen school / club. I have burned a lot of money and hours in the past on cheapest vs best value for money and whilst I'm grateful that the experience has taught me what I don't want or won't tolerate in a school / instructor, I wish I could have done it more cheaply.
The answer on RPC and PPL is hard as it depends on what you want to do, if all you want is to fly and just burn holes in the sky (metaphorically) on lazy Sunday afternoons OCTA, or even travel interstate, then RPC will be more than enough for you. As you develop, you will get a feel for what you might want or not want to do next, IE NVFR, IFR, flying overseas (USA, Europe etc) then a PPL will be the next step. With that comes more complexity in admin (medical, more exams etc) and some additional components not taught at RPC level (CTA, basic instrument flight and radio navigation ) but more responsibility and flexibility in terms of passengers and conditions. Good news is the hours all count and you're flying! Once you have both, you also can take your pick dependent on what suits your flying needs.
Again, the benefits of learning in GA and then going RAA at a later date or vice versa are widely debated and you'll find no shortage of opinions. Whatever you decide, you'll be flying. Moving from one to another isn't too onerous once you have the base skills built up. In terms of 3 axis RAA vs light GA, you won't find too much difference in how they fly and all the things you learn are directly applicable. Flying is flying and its mostly procedural and aircraft specific, which you'll find anyway as you move from type to type.
In terms of 40yo spam can vs light new RAA wonder, I'm a little less black and white in that. I find that GA aircraft ride bumps better in general than an RAA aircraft and make for a more comfortable ride, and being bigger can help with passenger confidence. Also, depending on where you go, there's no hard and fast rule saying you need to fly a 40yo GA aircraft, again you just need to be prepared to pay for the privilege, which again is a value for money thing.
As with the other posts, the RPL / RPC thing is a bit of a weird middle ground, and not too across it in detail so can't offer much there.
Hope that helps with your decision.