Depends on how and when the wine/liquer is added. alcohol has a lower boiling point than water. With sauces, etc a good cook will let the wine simmer until it creates a reduction of concentrated flavors. The alcohol when not reduced give the food an off-flavor.
The same thing goes for flambe cooking. Cherries Jubilee, Bannanas Foster etc. The idea is to use the alcohol burning to cook the food in a dramatic table presentation. the alcohol burns away and cooks the food and concentrates the flavors in the dish. I also looks kinda awesome!
In the case of adding liquer to fruitcakes or rum balls etc, The liquer is added after cooking, so you may want to avoid those if you want to cut down on alcohol consumption.
Nope... As long as it's not a drink! :) When they cook food with alcohol the alcohol burns off in the process leaving the consumer with no alcohol entering their body. You may need to be aware of some desserts that are prepared with alcohol but as far as your lunch or dinner.... no worries!
Trout
No i doubt it, however if you are really worried about that avoid italian foods with gravies. They usually contain cooking wines. Also many types of cakes (like rum cakes and such) use liqueurs..However, I really would be amazed if something like that caused a positive breathalizer test... Did this happen to you?