Fascinating to hear about US wedding customs - I had no idea.
Do you have Wedding Lists at all? In the UK, you tend to have a List at a classic Department Store, so people can pick something at the price point they want, and the bride/groom know they'll get something they want (traditionally useful stuff for starting a home, though this is more arguable as most people have it all by the time they get married).
Had never heard of the plate concept & don't see how you find out the value of the plate? I don't think UK people would spend $250 but then these days we are '(albeit ex) Euro-poor)'.
Of course, all these things vary depending on demographics - middle classes etc.
Charging is a tough one - if you have to, then I think you have to explain to your guests why, make sure you're keeping things to a minimum, i.e. if people know you're short of cash & aren't being profligate, they'll be more understanding, as they want to celebrate.
Kids - yes, unusual to not have them there, as finding babysitters a pain in the ass etc. - more likely only with younger people getting married.