It really depends on your preference. Personally, I am f2p and I still enjoy the aspects of the game, if anything being f2p forces you to be more creative and innovative with how you play and spend coupons. Others may like spending money to get ninjas or items faster, but eventually you'll get the same items if you play regularly, just takes longer.

As for events, Lucky Board is the best event for starting servers. I'm not sure about the ingot events though, but I suggest you invest your ingots in Monthly card and other high-return rebate deals.