If he has had the abdomen issue for a month and is doing fine it seems it isn't a issue for it.
The bend where does it happen on the abdomen (top or middle) and does it bend nearly straight when hanging upside down? A better question might be is it truly a bent abdomen, or is it simply bending it normally? As mantid nymphs can bend their abdomen nearly vertical for balance, but as they age they do it less, especially as a adult as their wings tend to get in the way of doing it (then they use their wings for balance).
A mantid only gets it's wings when it molts to adulthood, as such it will not molt again (adults are done growing and do not molt). The book will indeed help answer many questions, of course feel free to ask here if you have any. Regarding the sex
take a look at the link as mentioned as depending on where you start counting that will change your count number too. Females have 5 segments and males have 7, with a count of 6 that could be either.
The leg problem can be common and tends to be caused by lack of moisture/humidity, bad/lacking grip surfaces, feeders in the habitat during the molt, and from handling the mantid before it hardens (24-48 hours to fully harden). That said it can be a issue for various reasons for anyone.
As a mantid molts it will anchor it's legs into the lid, then pull itself usually half out of the old exoskeleton. It will sit drying out for 30 minutes to 2 hours in the half in/out position to harden some (as they are extremely soft/delicate and any stress/touch/movements can cause them to rip/tear or harden in a bad position). They then will finish pulling out of the old skin often pulling itself to the lid by using the old skin or nearby branches. If anytime during the molt the moisture/humidity is too dry it can become trapped in the old skin and bent legs is the most common outcome. This is because the skin dries out shrinking and hardening in place before it can get out of it, and the soft leg is pulled like taffy distorting it or drying in a bad position.
If it looses it's grip it will pull free injuring it's legs typically, or raptorial forearms, as it was not ready to remove them yet (or the grip caused them to be twisted). If the old skin looses it grip and the mantid falls during the molt, that is nearly always fatal or causes such deformities that the mantid rarely survives.
Given the leg, abdomen, and wing issues it is likely the mantid did not dry enough before it left the old skin (if caused due to a loose grip or a complete fall I have no way to know, but can say it was somewhat dry when the issue occurred). Sadly though legs and wings are common molting issues (less so for experienced keepers). With the wings it tends to happen due to a lack of space while they dried and tried to inflate.
