Four foot beds are a bit narrow for two rows of asparagus and a bit wide for one row. For example my beds are three feet. If you make two rows, plants will crop a little more in total at first, but become crowded in time.
I would go for one row and use the space along edges for other veg, in the first two years at least.
I am not convinced you need to ridge the soil unless it lies very wet in winter. I don’t ridge, and plants grow fine with similar compost to yours, on top.
