Seeds certainly don't get better with age. I've read many times that you can check their viability by placing them in water. If they sink, they're good. If they float, they're not. I wouldn't wait to plant any that are still viable.

Unlikely... and probably not fertile unless someone set out to fertilize them in the first place (need both sexes of plants for fertile seeds to even develop). Cycads will often develop smaller seeds if not fertilized, but these will never sprout no matter how fresh. 4 years is a long time for any cycad seeds to stay fertile, though.