Not much info. Why is there increased pressure?? Well, city water, pressure regulator in the system?? Pressure does not have anything to do with temp. A thermostat only looks at temp. But pressure can definitely affect temps at pressure balanced fixtures, like showers.
All day or just for a minute when the first person turned on a faucet or shower?
When cleaning anything including baby diapers, it is better to sweep off or scrape off as much solid and semisolid material as you can first. (1) Less cleaning fluid or detergent needs to be used, (2) Less of a mushy mess which in turn means that bleaches or disinfectants will be more effective.