Food photography, or any commercial photography for that matter, is never a matter of a couple of minutes. Even drop-and-shoot photos take time: you have to build the set and fix the lighting. Yes, most clients, familiar with point-and-shoots and cell phone cameras think it's all a matter of framing and firing: disabusing them is one of the first things we have to do.
Regarding DOF, it's a creative decision and not a tenet set in marble. If you have a busy background, you have to reduce your DOF; if you're shooting against a seamless, you can stop down to very small apertures. It depends.
The background is a creative decision too. Do you want the photo to be 'environmental' or catalog-like looking? Select the background accordingly then.
Whilst one light is far from adequate, it's absolutely possible to get very good results with a flashgun and some ready-made or impromptu modifiers. Position of the light is critical.
This is a basic, 'one light', pretty common setup for food photography:
And this is an image obtained with it:
Not shewn in the first photo, but used for the second one are fill cards and/or reflectors. These are a must in food photography, because the rule is: food does not like to be litten from the front
. Mirrors are a required piece of equipment as well: they effectively become a second light, or third, or fourth, depending on how many and how you use them.
Additionally, if you have a north-facing window, you have an additional light of diffuse quality.