Would my giving an incorrect DOB and/or SS# have legal consequences?
I think there are only legal consequences in situations where you would be committing perjury by giving false information.
If you apply for a credit card, and you deliberately give them an incorrect SS# they will just deny you the card.
If you're trying to defraud or mislead a government agency (IRS, Medicare, etc.), and you give them a phony SS# you'll likely wind up in a heap of legal trouble.
If you go to a free seminar, and they ask for your SS#, you tell them it's none of their business.
If you choose to give them false information, there would be no legal consequence to you since they have no legitimate legal reason for the request or legitimate legal authority to penalize you for giving them false information.
People lie about their age all the time. Again, unless you'd be committing perjury by doing so, don't worry about that.
If you want to go to that free seminar, and listen to their sales pitch, feel free to give them an incorrect DOB, and tell them to get lost if they ask your SS#, or make one up if feel too wimpy to do that. And demand your digital camera, even without giving out info like SS#'s, even fake ones, since the offer of the camera is simply connected to your attendance and sitting through their spiel.
If you attend that "seminar", expect to wind up on a lot of sucker mailing lists, with all sorts of offers, and you'll likely get a lot of unsolcited phone offers as well.
I once went to one of those freebee seminars, simply out of curiosity. They didn't request any sensitive identifying info I'd want to protect, but the sales pitch was extremely dull, the free give-away was such junk I left it there, and the cookies they put out weren't worth wasting calories.