Documentation Center for our games and mods
Most items in the game are used on self, they can provide an immediate boost (Health Pick) when used, or modify your skills and statistics for a period of time. For example using Lock-Picks will increase your related statistic for 2 turns. The system can seem a little weird to those used at using a specific item on a specific target, however the result is basically the same.
There's plenty of food available in most shops. Energy drinks and coffees are cheap and help in staying awake.