Is reagan speech a trustworthy source about the effects of reaganomics

No, it is not,  A speech by Reagan is a biased source, The speech would attempt to cast Reaganomics in glowing terms. It would be better to look at economic indicators such as the unemployment rate, the GNP and GDP as well as the stock market, housing starts, economic index, etc.

the best description of postwar writers might be progressive.

following the war, writers showed a tendency to work on artistic or social matters rather than political themes. while postwar literature may not have been the greatest period of english literature, the themes provided excellent critics a high number of novels. such examples include anthony burgess, anthony powell and frank kermode, all of which can be placed under the progressive view.