im going through a similar process too....
registries can always change so don't feel like you are making a decision that you have to stick with.
when it comes to over registering be careful because you may end up getting something that you don't like and something and not getting something on your registry that you do like
so much stuff nowadays comes in huge packages.. for example you can buy like 200 pieces of silverware at once... but usually you can split it up into multiple placesettings. this allows more people to buy stuff.
at macys you get all kinds of deals by registering. for example, if you register for more than 400 dollars worth of a specific brand you get some free gift. also, you can get like discounts for the future if you ever decide to complete the registry yourself.
and.. if you really want something.. you can register on amazon.com