camber and allignment also plays a role

Camber and alignment out will only make the tyre worn either side. tyre too much air or pressure will worn in the middle part. if both sides worn equally, then it should be low pressure. Front tyre worn faster because of the engine weight, front wheel drive and steering of tyres. front tyre pressure should be greater than the rear. Never trust the tyre pressure sticker on your car or booklet. different tyre brand different pressure even though same size.

Going around turns at 60 is depending on the turns la. If sweepers, 60 is very slow. If U-turn then 60 will make your tire screeching already.
Age does not play a part in tire wear, more on the elasticity of the rubber.

If camber is too negative, then usually it will wear on the inner side of the tire. If too positive then will wear the outer side.
If too much toe out, also will wear inner side more. If too much toe in, then usually will wear more outer side of the tire.
If wear out both inner and outer side, usually tire under inflated.

Why rear still ok? Because front does a lot more work for FWD cars (putting the power down and steering the car at the same time). Weight distribution of FWD cars are also more at the front, hence more pressure put on the front tires. On top of that braking also is much harder task on the front tires.
So normally front tires for FWD cars would need a few more psi of air/tire pressure. If you put the same as the rear then the front will tend to wear out much faster. Even if you give more pressure to the front, it will still wear out faster, hence you still need to do tire rotation to even out the wear all around.

size?

Booklet is just a guide. check your tyre every 5000 km then you will know what to do with it.

You're supposed to rotate every 10K. It's possible for the front to be worn out much faster if you under inflate and you don't rotate, then do a lot u-turn at 60kph.

You can just buy 2 tires and use them at the front since the rear are still good as you said. Different brand is still ok as long as the same for each axle. Might not be ideal but still very much acceptable.

Rotation does not necessarily need alignment if all your tires are more or less the same condition. That's just the workshops trying to make more money out of you! The rotation it self should be cheap la, only jack up the car and open bolts what? Heck I used to do it myself few years ago!

Some tires will screech more than others. But yeah, no screeching means in general not too bad. I often corner until my tires are screeching loud but yet they are still in good condition after 30K km!

Again as I said before, it's not true that tire rotation always have to be followed by alignment. Those who said that don't know anything, or they are workshop owners who want to make more money! Anyway it's up to you if you want to believe me or not, it's your money after all so do what ever you think is right for you.

In terms of tire pressure, well the look of it can give you some indication but not enough. Normally the tread pattern have to lie pretty flat on the road.
If you prefer less pressure then that explains why your front is worn out already on the sides.

read the tyre wall. it indicate the tyre max pressure.

Yes I would if I'm still using the std rims though.