1) you need a proper fuel system no matter what size shot you run. you'll also need colder plugs.
2) the ideal way to use nitrous is with a window switch that allows the nitrous to start flowing above a certain rpm and shut off at a certain rpm at wot. push button's are for fast and furious wannabes. the best way is with a programmable ems.
3) dry is ok for small shots. wet is safer for larger shots. direct port is the best and also priciest. dry injects only nitrous through the nozzle and rely's on the injectors to add more fuel. wet injects nitrous and fuel through the nozzle. direct port is the same as wet but each intake runner is tapped with a nozzle. if a direct port kit is not available for your engine, fab one up with the correct nozzles, lines, solenoids, etc.

this is from my basic knowledge of nitrous