Just on the re-proofing thing - I have not used a reproofing agent on my rain jacket, just washed with wool wash detergent @ 40ºc in the machine and then hung out to dry. I've washed the jacket several times and it's still perfectly waterproof up to about an hour in heavy rain. And even then it's very slow to properly wet through. I guess it depends on which particular jacket/material how it responds to washing.
Just on the re-proofing thing - I have not used a reproofing agent on my rain jacket, just washed with wool wash detergent @ 40ºc in the machine and then hung out to dry. I've washed the jacket several times and it's still perfectly waterproof up to about an hour in heavy rain. And even then it's very slow to properly wet through. I guess it depends on which particular jacket/material how it responds to washing.