This public announcement brought to you by scientist who are having no sex at all! I thought this was a great selfie!
#1. Don't think so. #2. Only in rare occasions when in extreme excess. #3. Maybe delay it a bit, but not prevent. More is better! #4. See #1 #5. Only once. (That I can remember.)
1: it numbs the vagina - good! Better to take a pounding with 2: it effects his erection - Viagra 3: it can prevent either of you from getting off - only if you're doing it wrong 4: it stops her from getting wet - that's what lube is for 5: it makes you more likely to forget protection - rattle snakes and condoms, two things I don't fuck with