G'day mate, and welcome.
I cant answer all of them, but I can give you my experiences.
I am RAA Rec Certified pilot, and aircraft owner. The first question I would ask is why do you want PPL? Do you need it? As in, do you expect to fly more than just you and 1 Pax etc etc? Can you get away with it in RAA. When you answer that question, you will start to get an idea on costs etc. I will give a small comparison to start, but there are other factors,
RAA Cert with a Nav - you could realistically gain this for as little as $8000. Maybe less depending how you go.
PPL - Somewhere around $16,000
RAA Aircraft are cheaper to maintain (you can even maintain it yourself) If you are PPL and in the GA space, then your maintenance costs go up for sure.
My aircraft carries 2 and has about a 6 hour endurance (less with a good reserve) and burns regular unleaded at about 17L/H. In a larger GA bird, you will be burning AvGAS ($2.50P/L) and more litres per hour depending on the bird.
My aircraft is in rented hangar space that I share with the owner of the handar. Works out about $60 a week. But you could get it more, and you could get it less.
RAA registered birds can start pretty cheap, but can also cost a fortune, depending on what you want.
The PPL learning curve is obviously more than the RAA learning curve. It will take you longer in the books, and in the air - for obvious reasons.
So the first question you need to ask yourself - Do you NEED a PPL? Then you will know what way to head.
I fly RAA because it allows me to have fun in aviation, at a reasonable cost. If I was in GA, I don't think I could afford it.
Just my 0.2