I can't comment on the accuracy issue, but periodically (once a month?) you probably should let your iPad completely run down, but you won't hurt anything by "topping it off" as required. They really haven't been out long enough for anyone to give conclusive long-term evaluations about the best way to get the maximum longevity.
According to Apple, "A properly maintained iPad battery is designed to retain 80 percent or more of its original capacity during a lifespan of up to 1,000 recharge cycles"
Of course they fail to say what a "properly maintained" battery is! The iPad hit the streets (in the US) on April 3 which means it has only been out a little over 110 days. Even if you fully charged your iPad every day, it would still be nearly 3 years before you hit 1000 cycles. Even when you hit that magic number, it won't instantly stop working but will only (theoretically) keep losing its ability to hold a charge over time.
I have said this in other posts, but in 3 years, I am pretty sure I won't even be using the iPad I have now so I am not really going to sweat it!