Like intangible-tangerine said, it varies by place and time. For example, we know that authors like Sallust used archaisms like "maxumum" rather than "maximum," so superlatives probably used to be pronounced that way in some earlier form of the language.

Generally, though, they used Classical. Church Latin refers to the Latin used by later Christians in the Medieval period in into modern times via Vatican City.

Remember though, this is all subjective. Until we can meet a Roman and ask him/her, we won't know for sure. So never.

You'd need to specify a time period and a location (unless you just mean within Rome itself?) and a social class as all languages are subject to phonological change over time, distance and social contexts. That's the reason why we don't agree on whether 'Celt' has a hard or a soft C sound for example, because different Latin speakers at different times and places pronounced 'C' differently.