My boyfriend and I find it sexually satisfying for some reason when he urinates inside me, would this affect me long term? (e.G., reproductively?) etc

Well..... Urine is sterile, but i suppose it could increase your chances of getting a vaginal infection in the same way that douching can cause a vaginal infection. It surprises me that he is able to do this. If he has an erection adequate for penetration, then it should be extremely difficult for him to urinate while he has the erection.
Unlikely. I have not once in my career seen this question addressed this way before, and there is no clinical evidene one way or another. My guess is 'no.'.