Any physical variables come in 'canonically conjugate pairs' cannot be simultaneously measured with arbitrarily high accuracy. Canonically conjugate pairs are those variables whose corresponding operators do not commute; means the order in which they occur when they form a product makes the difference. examples: position and momentum, energy and time, angular position of the momentum vector and the corresponding component of the angular momentum.
Uncertainty comes with pair of variables, not with a single variable. The pair of physical variable whose corresponding operates do commute (not conjugate pairs) can be measured without uncertainty. For example, time and position of a particle can be measured simultaneously and is not limited with uncertainty.
Of course, there are uncertainties associated with all the measurements. Whatever we measure may not be perfect, always there will be uncertainties. Those uncertainties are related to experimental or instrumental limitations. But the uncertainty what we see in the quantum world (Heisenberg's Uncertainty principle) is inherent in nature. Even with a perfect instrument/experimental setup, this uncertainty will be there for the conjugate pairs!
Furthermore, if you are a beginner, "Alice in Quantumland" By Robert Gilmore would be interesting. Alice when she meet the electron, it is moving to and fro very rapidly. When she ask to stand still for a moment, the electron reply "I am afraid there is not room enough. However I will try". Then the electron slows down. This time the electron looks so fuzzy and out of focus and the electron say "I am afraid that the more slowly I move, the more spread out I become. That is the way the things are here in Quantumland".... So, the uncertainty associated with the conjugate pairs are inherent and that is the way the things are in Quantumworld! :)
Refer this for your question regarding electric charge: