Answers below:
1. What are the major pitfalls for new, married swingers? And do you think it's worth the risk of falling into one of these pits?
The pitfalls come from having poor communication and one or both partners possessing a jealous streak. This lifestyle is NOT for everyone. It is a common fantasy to talk about but the reality is much different. ANY jealousy that exists in someone is amplified 100x over when they're in a swinging situation. Imagine the guy/woman who gets a small jealousy feeling when their other half talks about someone from work, is a little flirty at the Christmas party, etc...change the "talks about someone from work" to kissing another guy while he fondles her tits" or "moans loudly as another man penetrates her"...yeah, recipe for disaster. I've seen a handful of guys just start boiling when their sexy female half gets a ton of attention while he gets little. News flash to the guys...your female half will get significantly more attention than you will. Be ready for it, better be able to handle it.
Along the same lines are couples who set too many rules. Making a list a rules hints at possible jealousy. Mrs and I see red flags when talking with a potential play couple when they start bringing up a list of rules. Yes, setting some rules is fine, but when the list is long, it starts to appear as if one of the couple isn't fully in, and rules are set to control their hesitation.
Also, when people drink a little (usually turns into a lot because of nervousness) and they're with other couples who are more experienced, rules bend. Sometimes couples will try to separate those new to the lifestyle, making it easier to bend those rules. I've known a few couples who had specific rules about kissing, soft swap, same room only, etc and within 15 minutes every rules was broken. I actually tried to intervene and help the couple out because they jumped into the deep end so fast.
2. Does AFF actually work? Or are there just too many fake accounts and accounts that are too old?
Can't speak about AFF but other sites (I won't specify) have been good for meeting quality people. Different sites have different pros and cons. You have to try a couple and see what works best for you.