Those who purchase a contract via resale are afforded the same benefits as those who buy direct. If you buy through DVC, you get some goodies when you sign the paperwork, but other than that, I can't think of any strong distinction.
The Member Homecoming is a brand new event, and the first of its kind. I kinda doubt that it will be an annual event, but that's just my opinion so far.
Cost was $299 per adult or $249 for Annual Passholders.
I should add that there was a DVC Member Cruise a couple of years ago, and everything I've read about that has been positive.
I believe there was also some sort of "Member Days" celebration that happened weekly last summer, but it wasn't nearly the scope of this Homecoming event. Maybe someone more knowledgable can fill in the blanks on that event.
Maybe they'll do something next year to tie-in with the Disneyland birthday celebration in California. Who knows?
So, to expand on my prior comments, I doubt you'll see a carbon copy of the Member Homecoming annually, but with all of the positive reviews coming forth, they'd be crazy not to continue scheduling SOME sort of special event every 12-18 months.