Insulate room over porch
An air barrier (housewrap) is quite specifically NOT a vapor barrier.

Vapor barrier should go on the warm side (out in primarily cooling, in for primarily heating) - look up the heating degree days and cooling degree days for your area as one reference, or ask yourself if you use the A/C or the heat on more days of the year.

A loose fill product (cellulose, for example) will deal much better with odd shapes and framing irregularities and voids. Densely packed cellulose can also be used without a vapor barrier as its vapor transmission rate is quite low as a bulk material, thus eliminating the issue of where to put a vapor barrier in a mixed climate.