Of course it can but this is not a good swap. If you wish to go to a 60 series tire then use 205/60-15.
No, if you are going to a 70 series tire then you will need to go with 195/70-15.
Yes, you can.
Yes, you can.
No, absolutely not. This is a terrible swap as the 205 tire will be 5% larger in overall diameter than the 195 tire. Your speedometer will read 57 mph at a true 60 mph. Power, ride, handling, braking, and fuel mileage will be adversely effected. If you wish to go to a 70 series tire then go to a 185/70-15. My advice is to stick with the OEM size.
Yes, a 205 75 15 can replace a 235 75 15. Be aware that this will reduce your load carrying capacity and may need more pressure.
OEM Standard tire is 195/65-15 Optional size is 205/55-16
No, that is a very bad substitute. If you want to go with a 70 series tire go with a 195/70-15 which is a great substitute.
Yes, you can
You can but it is not a perfect swap. Make sure you have the same size tire on each axle.
Yes, but if you go from, lets say, a 195/70-15 then go with a 205/65-15.
They are pretty close in overall diameter as the 205 will be .3" smaller. Your speedometer will be .7 mph fast with the 205. Your engine will turn an additional 10.1 RPMs every mile driven with the 205. The 205 is a good swap if you want a wider tire.