how hard IS a century?

[Pedal Wench]

Also, should you take in carbs every 30 or 45 minutes--stuff like Carb-boom, Cliff shots, or more substantial chewy fun food?

Whatever you can stomach! Really, you'll want to alternate so you don't get bored, and really whatever makes you happy. I use centuries as an excuse to try out all the new bad candybars, although I pay for that with the sugar-crash that usually follows. Oh well.