Weddings can be a lot of fun, and they can be a bit of a drag. It depends on the people attending. As for insurance, that depends. Insurance for what? Would the policy cover theft, liability? Personally, I think insurance is a good idea, but you have to be specific as to what coverage you are getting, and pay close attention to the exclusions in the policy. There is no such thing a generic insurance policy. The policy language spells out exactly what is covered and what is excluded. Also consider the deductible. A low deductible means expensive premiums and a high deductible means you pay most of the loss. Typically the policy is for property (your gear) or inland marine (transporting equipment).
As for licensing, if the venue is a typical wedding venue, the venue will cover the licensing, just like a bar would. If the venue is a rented hall, then you should discuss that with the bride and groom. If they want you to pick up the licensing fee, then consider that when pricing your gig.
Watch your volume. You can get louder as the people get bombed, but watch the volume. Learn a broad repertoire. You will get a lot of requests. You will need a good mix of dance tunes and slow tunes. The bride and groom get a chance to dance with their respective parents. You will need to honor those requests. Learn "Color My World" and "Feelings". Remember, nowadays a wedding is something most people only get to do two or three times in their lifetime. They want to have fun.