The unit is not shown but it is volts. You might want to double-check if you have specified all parameters of your simulation correctly (e.g. the timepoints for which you perform the tdnoise analysis). The Total Noise option might not exist in older versions (I am using 5.0.33), you will probably get the total noise by default in your version.

The value you get is the standard deviation of the Gaussian distribution. The peak value will be higher, depending on the probability with which it occurs. Like I said, in many cases there are other effects that generate larger amounts of jitter than the intrinsic device noise.

The formula given there applies to a sine wave with stationary noise but not for the general case of an arbitrary periodic signal with cyclostationary noise.