I haven't taken the time to review the draft, yet; so I may be way off base with this comment. Gender guarantees are not always given, it depends - or should depend - on the ease with which an animal can be accurately sexed at the age they're sold. For example, some breeders of arboreal boids won't probe or pop neonates because of the potential for damage/harm.
A lot of people SAY that gender doesn't change, so a gender guarantee shouldn't have a time limit; but, in reality, few people are willing to make something like that right a year or more down the road. I've received several incorrectly sexed snakes over the years; and I've never received any form of compensation unless I caught it immediately. That said, I've never met anyone that was 100% accurate, 100% of the time, when it comes to sexing reptiles. Set up a reasonable time frame during which the buyer can contact you about such a discrepancy - maybe 2 weeks, as an example. Once notified, you establish the options: return for refund, return for exchange, keep with partial refund, etc; realizing that if you sent the wrong gender, you should eat the return and subsequent shipping because it was your fault. If the customer returns a snake based on a complaint of incorrect gender, and it is found that he/she was mistaken, it is their expense