I believe you're confusing bars of pressure (1 bar ≈ 15psi) with volumes of CO2. The 28 PSI is more for if you had a carb cap on the bottle and hooked your bottle directly to a CO2 tank. Refer a force carbonation chart and you'll see 28 PSI achieves 2.5 volumes @ about 65F; ideally your beer would be at mid 30F and only need about 10-11 PSI. You should be able to follow any priming sugar calculator just fine.

You need to clean AND sanitize any bottle you decide to use.

You treat the plastic bottles exactly the same as you treat glass bottles No difference. One caution: the screw on caps will sometimes crack and leak CO2 as the pressure approaches 3.0 volumes. Of course the pressure in the bottle is highly dependent on the temperature that the bottle are stored at. Early in my brewing hobby I stored the bottles at temperatures ranging from 60 to 65 degrees Fahrenheit in Fall Winter and Spring. In Summer the temperature of the store room rose to 72 degrees. Some of the glass bottles exploded - what a mess. For the more highly carbonated plastic beer bottles the screw-on top would crack and let most of the CO2 out. I don't brew highly carbonated beer anymore.

I wash mine just like glass rinse out immediately fill with PBW and then sanitize with StarSan before use will use bottle brush when necessary but if you rinse and wash immediately usually a brush is not necessary.

I treat mine exactly the same as any container. Wash with PBW then sterilize with Starsan or Iodine.

Wash by hand...yes sanitize after . Watch the caps...some of mine didn't seal well...i only used them for root beer for kids

I received my bottles put them all in the dishwasher and they are all deformed and shrunk. Careful what setting you use

I wouldn't again. Two deformed on the bottom rack. Maybe try on the top rack? Darren

From personal experience washing them I would say so…

Yes TOP SHELF ONLY!

These caps can be reused. They have a soft gasketting material under the lid which will seal when reused.