Go here and pick out a true parallel-flow ("PF") condenser sized appropriately for the cutout in your radiator core support panel. Bigger is always better with a condenser; too big is not a thing.
Probably. Take a look at this exhaustive set of tests: R12 and R134a (and a few others not worth thinking about), with tube-and-fin (old type) and parallel-flow (new type) condensers, at a variety of in-car ambient temperatures. Take a look at the differences in vent temps and high side pressures with the old versus new type condenser, especially as demand rises (higher in-car ambient temp).
