Various fluid system and fluid operation embodiments include a first valve structured to permit fluid flow therethrough in response to application of positive pressure at an inlet of the first valve with an outlet of the first valve in fluid communication with a portion of a fluid system; a second valve has an outlet in fluid communication with the inlet of the first valve, and the second valve is structured to permit fluid flow therethrough in response to application of negative pressure at the outlet of the second valve; and, an inlet/outlet port in fluid communication with the inlet of the first valve and the outlet of the second valve at a common refill/evacuation location. Systems and methods incorporating electronic valves, configurations to multiple check valve assemblies, and modules of valve assemblies are also provided herein. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.